I'm inclined to think coeliac is actually more common, the research I've seen (can't remember where, will dig about and see if I can find it) stated that about 1 in 100 people have coeliac, while the information books my hospital hands out says that IBD affects about 1 in 200-250 people.
I think it's more that once you're used to the diet and have learnt the dos and don'ts coeliac is easier to manage. It can be a highly frustrating condition at times because it is limiting when trying to eat out, and many people don't take it that seriously, but I tend to say I have an allergy in restaurants and they are really good (my lips and tongue do swell so it's almost like I am allergic as well as the internal issues) .
IBD on the other hand is intrinsically hard to get controlled and keep there, medications can have nasty side effects and surgery is scary and often complex. IBD has a higher complication level because treatment isn't 100%. Although coeliac can be very serious and the symptoms are nasty, if you stick to the gluten free diet then the vast majority of sufferers lead healthy full lives. So I think for those reasons it is less reported if that makes sense?