I was wondering since it's strange to me that the whole presentation was hosted by Bill, someone might argue that it might be due to the new version of the Nintendo Directs but the European Direct was still hosted by Satoru Shibata so that can't be the case.

Usually I wouldn't care much but after seeing what happened last year with Mr. Iwata I can't help but feel a bit worried about Reggie... Of course Mr. Iwata previously had various health problems but nonetheless it could be...

Might be several reasons

It's probably just a case of them realising that Bill is better-positioned to deal with the normal Directs, so Reggie only deals with the big ones, like a pre-E3 Direct, or one where they're going to announce something big.

His body wasn't ready

Maybe he is preparing something big.

He might be waiting for the E3 DIrect instead of a regular Direct, specially considering the amount of things that Nintendo will have to show on E3.

I doubt there's any significant reason to it. He'll likely show up at E3.

His body wasn't ready.

Reggie doesn't appear in every Direct. I also did not appear in the April Direct last year.

His body was in fact too ready and if he showed it off it would potentially cause a great deal of harm to viewers.