The biggest ‘con’ of returning in general is wasting your time and neural cells, at the very least (possibly also money), and potentially getting stuck in the cycle of hope, hype and disappointment again — the one you apparently decided to escape three years ago for some reason.
The biggest ‘pro’ is saving a lot of the aforementioned and likely having a happier life in general as a result.
Oh, they’d also give you a free deck — you know how it goes…
Speaking of which, I might as well link this one (re that cycle), for example: Im so ready for 2025 core set - #19 by SparkyElf-2852 (see also other posts in that topic).
With that said, cards from that free deck will likely be more useful in Standard after a rotation, in addition to what you pointed out yourself.
Ultimately, of course, you’re your own man — make your own decisions, I just wish for your choices to be informed and for you not to harbour rather typical delusions about this game. If you think it’s fun to play it for a while and you know what you’re doing and why — go ahead, why not, I suppose, but if the game ‘plays you’ instead — it’s probably a good idea to discontinue (again)… or not even resume it in the first place and give in to the temptation. 
That’d be my suggestion.
Ye-e-e-e-ah… The topic I’ve just linked above covers that part, I think.