Before Bo3 there were a lot of players asking for it, less for the anti-donk, than for the boost it gives to skilled players who wanted an answer to random losses, especially in the early rounds. Just adding more rounds doesn't fully answer that desire by itself. It's still a lot more difficult, both mentally and mathematically, to claw back from 0-2 off of bad opening hands than it is to deal with two midday or late-day losses.
Also, when considering getting rid of Bo3, take a look at real examples like the one in Alex's 'The Clock Struck 9.' His first round was LWW. In Bo1 that would have been a loss and his anti-meta deck would likely have faced all sorts of non-meta decks that it wasn't designed for after that. That sort of thing happened all the time back in the day and it affected not just deck choices, but drops, overall tournament experience, and much more. Going further, if you just take Alex's first matches as would have been the case in Bo1, his final record day 1 would have been 5-4 and he wouldn't have made day 2, let alone finish 9th overall.
With all that said, I'm firmly in the camp that current events are WAY too long. As an older player those days take a physical toll, not just a mental one.
I'm wondering if there might not be a comprise of sorts. Maybe the first three rounds of day 1 could be Bo3, and subsequent rounds Bo1. That would limit some of the impact of ties, but also still limit randomness in the early going.
And since 4 prizes has already been suggested I'll add that 30 card decks are a thing. Playing Bo3 with 30 card decks (& 3 prizes) is going to be faster and might be a fun format for day 1. Crazy talk I know.