THAC0 maybe be literally backwards and easy to make fun of these days, but when I discovered it (it was first introduced in a UK module years before 2E) it was a revelation and a significant improvement over attack matrixes that I found hard to read and necessitated actually having a book or a screen to run a game, while a single number was much easier to deal with.
I found it really worked best when player simply subtracted what they rolled from their THAC0 and announced the AC they hit (rather than using it to determine a target number to be rolled) and then the DM could say if that hit or miss the target AC.
That said, one of the things that have kept me from going back and running 2E is the work of flipping AC so I never have to deal with THAC0 again. It may never have tripped me up, but many (new) players (especially) got confused by it.