I dont think its silly, you just wont have as tight of spacing between gears but you will have the exact same range. If this would be an all out race bike I would say do a more traditional set up but if this is more a do everything kinda bike (road, cross, commute, maybe light tour) bike keep with what you are thinking and it will make for a super versatile bike.

I personally am running a compact crankset on the front and am about to put a 11-34 mtn cassette on the rear to ad another level of versatility to my bike despite the fact it race it quite a bit. (it also see's alot of commute's some tours, and long gravel grinders where a 34 would be nice)