Noone used Focus because of AP PTs, if you seriously think Focus is not OP you are living in denial.
No one uses it because its easy to counter and easy to heal through. Good teams did this magical thing called spreading out so healing the one big hit was easy to deal with. Hell, mudclots team ran two sorcs which apparently most people would believe to be an easy win against but they dominated the "two smasher" teams.
I think the big hit on smash is lulzy and when I do spec into it I do so simply for the laughs of a big hit. Aside from that though? No I really don't believe focus is OP because its a one trick pony and extremely easy to shut down which is blatantly obvious since smash has not been the "go to" spec in arenas and double smash didn't even last a month. Its strong in regs and strong in solo arena because most people in regs and solo are typically not that good.
But balancing specs around the lowest common denominator is a terrible thing to do. I've seen fighting games go from good potential to being horrible because they changed things to help out the terrible players who didn't use common sense.
With that said, I'm not against redesigning the spec. I'm not a fan of nerfs, but if they want to change this spec then do it right. Don't just outright murder the spec. Either redesign it into a single target spec or leave swelling winds/felling blow as is and just make singularity apply to one target thus keeping the aoe a viable aspect of the game while still maintaining strong single target burst. What they are proposing right now murders the spec's entire design which I am highly against, especially since the ability will still register as an aoe thus this new "single target" spec will still be gimped against 30% aoe talents.