Nice thought, however, we have to live in the now. We might not even see the restoration of the buildings during our lifetime. Even sedevacantist groups build new buildings, there's nothing strange about that. Some older buildings at certain locations may be even more expensive to repair and maintain, especially if they have not been in use for some time.
There's no doubt that the SSPX could simply have built additions to the existing Winona seminary, and saved many millions, but for various reasons, it preferred not to:
1) The ghost of Bishop Williamson haunts those halls, and the SSPX was eager to signal a new formation by building a new edifice for an altogether new (branded) formation (which would be more agreeable to Rome, and therefore conducive to "reconciliation").
2) By relocating to be near the Masonic capital of the world, the SSPX also telegraphed it was ready to come to terms with DeepChurch: All the reasons the Society formerly adduced as benefits to the central location in Winona, its relative isolation, proximity to airports, and vast acreage were suddenly forgotten, and now was touted the cultural benefits of being near Washington DC! What was once perceived as an enemy Masonic stronghold was now "culturally beneficial"). Soon it would be subservient to that Masonic government, closing its chapels upon order and even accepting its death jab (which +Vigano has noted is a kind of indelible mark like a baptism into the NWO).
See this long-forgotten article adducing the reasons and benefits of moving to Virginia, and see if you are convinced by the sincerity of the reasons contained therein:
https://www.winonapost.com/news/seminary-says-goodbye/article_6ebdbcb0-2213-513b-83a7-7baaefd5e9b2.html 3) Although the 2012 deal had fallen through, SSPX leadership was still resolved (perhaps more than ever) to achieve a practical accord, and the thought was that along with reconciliation would come vocations. Lots of them. Bishop Fellay had fallen victim to the same siren song as Dom Gerard, Bishop Rifan, and many others before him, who believed that regularization would open to the SSPX a huge field for the apostolate.
Yes, perhaps, but as noted by Dom Laurenco Fleichman in an open letter printed in
The Angelus, rebuking the priests of Campos:
"When your Fraternity was conducting the current negotiations, I spoke to Fr. Fernando (Rifan) on the phone. He gave me three reasons that he considered sufficient for going ahead and concluding the agreement, even though the Vatican has not agreed to allow the Tridentine Mass: 1) many new persons would rejoin Tradition; 2) we would have a foot in the door of modernist Rome for preaching Tradition; 3) we could still go back to our former position in case we were unduly pressured.
These are precisely the same arguments as those of Dom Gerard in 1988; to me, shockingly so. Firstly, because then you knew how to critique Dom Gerard's position, as was so necessary at the time. Second, because today the logical conclusion you are obliged to reach
is that Dom Gerard was right! He preceded you by ten years, which obliges you to believe that his assessment then was better than yours.
I think that the following affirmations are undeniable:
1) The new people that will join you will not desire to convert to true Tradition. They will come to you because the legal obstacles have been removed, and not for reasons of faith. They will be very sympathetic, but they will not be seeking the whole truth with the doctrinal conviction that leads souls to martyrdom; 2) Being in modernist Rome‑and this is proven‑invariably results in contamination by the guiding principles of Vatican II, administered in homeopathic doses until the fruit falls, as the St. Peter's Fraternity fell; 3) As for going back: who among them has ever returned to his former position? They would rather concelebrate with the Pope than go back. And if they did go back, what would become of the faithful in their parishes? Would they all go back? How many would be entangled over the question of legality? I consider such an attitude reckless; it does not take into account the constancy of the souls that Providence has entrusted to you. You regularize on paper a phony problem of excommunication, and the faithful have only to follow and obey, and then, tomorrow, to about face and retreat with you!
I cannot quite see in this the respect for souls the priestly life requires."
https://www.sspxasia.com/Docuмents/Society_of_Saint_Pius_X/Open_Letter_to_the_Priests_of_Campos.htm
And is this not precisely what has transpired with the SSPX? People coming to them because BXVI allowed the TLM, and/or because Francis granted faculties for confessions and/or marriages (i.e., they have come because the legal obstacles have been removed, and not for reasons of faith)?
Leaving aside other considerations, such as Lefebvre's rebuke to Dom Gerard that it is the superiors who form the inferiors, and not the other way around, and other quotes regarding the dilution such an influx of conservatives would represent to the quality of the faith preached and received in the Society, Lefebvre also noted the impossible situation which would arise in seminaries attracting two opposite types os seminarian: One that is pro-Rome, and one that is anti-modernist. And in fact this did happen in the seminary. But the Society found a solution for this too: A purge of the Williamsonites, and of resistance priests from the Society. Quite a price to pay! "We have rediscovered our profound unity" indeed!
Those measures, combined with the new strategy of Francis to regularize by location and incrementally seemed to have succeeded to some degree in opening to the Society the wider apostolate it yearned for.
But whether the trade-off (quantity for quality) was worth it is debatable to say the least.
These in any case were some of the reasons for the new seminary.