I mean, it was a more recent decision to purchase a new fleet. They were planning on rebuilding and extending the life of T1s through the 2030s, up until quite recently.
Even that was too late to be waffling on the fate of the T1s, IMO.
But it begs the question - why, before they had even secured a commitment of funding, did they decide to walk away from the T1 life extension plan? Because politicians have shown themselves to be so reliable and trust worthy that they could've just counted on them funding a replacement fleet?
The lessons learned from the CLRV and ALRV rebuild process is that it cost far more and produced far fewer results.
I'm not sure anything can be deducted from the CLRV and ALRV. The CLRVs didn't receive any kind of comprehensive overhaul, there were certain cars which had body rebuilds done in the first half of the 2010s, but it was not a complete, top-to-bottom rebuild, and it had little effect on reliability - some of the most reliable cars, which held on until the end was drowing close, were the ugly, rusted out ones with faded paint. They were so reliable mechanically they rarely made their way to the shops, and the consequence was that they looked awful.
As for the ALRVs, it is my understanding that the "refurbishment" (itself a pretty generous term) they got was largely cosmetic, they did little work on the mechanical innards, and the ones that got work done were not really the problem. Part of the problem also was that the ALRVs were always lemons, and sometimes, no matter what you do, things can't be made better. The T1s have historically been one of the most reliable fleets the TTC has ever run, if not the most reliable.
Maintenance is very important, and even more important than rebuilds is the daily maintenance. If we increased our daily maintenance standards, we could probably go many more years. But, it always boils down to costs, as equipment ages, the cost to maintain goes up.
Day to day maintenance is of course important, but as a vehicle ages it can encounter problems such as frame corrosion/fatigue or degradation of vehicle systems which daily maintenance wouldn't really cover. If it was as simple as upping our daily maintenance standards, we still could've been riding around in G1s and M1s (which I would've hardly minded). At some point you reach a crossroads where you have to decide to rebuild or replace.