Is it me or way more supports are taking ignite now?

Ignite is better if you're playing "support" Cho'Gath.

I know this was norms but I'm still laughing over this. http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2125879868/215814139?tab=overview

It's really a preference. Into a double AD comp most would probably still run exh, but the exta kill pressure in lane is really helpful in the snowbally meta.

season 3?

Ignite is better if you're in a kill lane like thresh lucian to secure kills.

If you need kill pressure or you really need it to suppress the super-sustain champ later in the game, then you go Ignite.

Obviously you'll do it less often than Exhaust, but there are cases where you care less about reducing damage taken and more about taking them out.