I don't think the character of Joey being smart would have had a negative impact. However, him being not so bright sure has a funny impact on the show. If his character wouldn't have brought that, they would have found another way to bring it in. Now in saying that I'm glad they did Joey's character the way they did. It's a great show and I'd hate to see it as being different. I think it would have been like Chrissy on Three's Company being smart. Still would have been a good show but better the way it was ultimately done.
The show was sucessful in part because of the character, but he could have played the charcter more intelligently and been just as successful by playing to the top of his intelligence. We will never know though because the character was not played that way and it never will be.
No, I think that the actors on Friends got the character development just right. Also the chemistry between the actors was perfect. Had any one actor done things differently, it would have thrown the whole balance off. The show probably would not have been nearly as successful if Joey had been played differently.
Each Friends characters was very distinct which is one of the big things that set the show apart. Most sitcom characters today are very flat and a lot of ensemble casts have very similar characters. Friends was unique in that it showcased six very unique personalities in the six friends. I think Joey needed to be somewhat "dim" on the show to balance the other Friends. Ross was the intelligent male character. The show didn't need another Ross. It needed Joey.