Daniel Bryan's so called "stupid gimmick" helped him to reach a level in his career he'd never been close to before.
What Bryan has shown over the course of the past 15 months or so is that he not only has the ability inside the ring, something that's been known since long before he came to WWE, but he also has the charisma & passion to make fans care about him as a character. Before beginning his slow heel turn late in 2011, Daniel Bryan was a bland, generic babyface. He went from being a bland, generally uninteresting wrestler to being one of the most over wrestlers on the WWE roster within the span of about a month.
Daniel Bryan had an amazing year in 2012. Not only did he win the World Heavyweight Championship, but he has a meaningful & significant run with it. His feud with CM Punk for the WWE Championship, after his feud with Sheamus over the WHC ended, also resulted in some of the best wrestling matches of 2012 in any company. He goes from there to form an unlikely tag team with Kane and they became, arguably, the most entertaining tag team in wrestling in 2012. They were certainly among the biggest & most pleasant surprises in 2012 and were part of some of the legitimately funniest moments seen on WWE television in years. On top of all that, Kane & Bryan helped to revitalize tag team wrestling in WWE. It's not perfect, but tag wrestling & the tag team titles mean more in WWE now than they have in many years. The tag team scene has taken a backseat during the WM build, so I'm hoping WWE gets back on track in the post WM season.
As I alluded to earlier, Bryan's comedy character has helped to get him to another level in his career, one where he's a pretty significant draw & money maker for WWE. It's one that's shown he has a good deal of personality & charisma. Because Bryan has shown that he has the stuff not only in the ring but as a character & personality as well, he has the potential to be a long term player in WWE.
So yeah, Bryan's "stupid gimmick" is one that's made him a big, marketable star in WWE. I guess 10,000+ people cheering & chanting for him every night and being invested in whatever he's doing isn't as good as being personality challenged milk toast indy wrestler.