I am a huge fan of vince clarke and one question thats always been on my mind is why he left depeche mode. Does anyone know why? I mean i still love depeche mode with martine gore as the writer but I would like to know just how depeche mode would have ended up (as far as music goes) with him staying on board.

He left because he didn't like the direction the band was going towards. He is reportedly to have said their album sounded too Pop, which is ironic since he went on to do projects like Yazoo, Marlowe, The Assembly, and Erasure (which is even more Pop-pier than DeMode!). If Vince would have remained in the band, all the songs from Yazoo and Erasure would have most likely been added to DeMode's repertoire since he was the writer and composer of the first album. This means we may have missed Martin's songs from later albums and maybe even a conflict of artistic direction and interest between those two. Personally, I like the way things turned out. It would be a shame if DeMode would have broken up later on because Vince and Martin didn't get along (as is most of the cases where two genuises are in the same band).

Another story:

According to various sources, Vince left DM after "Speak & Spell" since he was (or better said still is) extremely shy and didn't felt very comfortable with the sudden success and the prospect of prolonged touring.

As much as I like Vince's later works in the aforementioned projects, I think that his leave was good for DM's career since his sounds are a bit too, ahem, static - basically, Yazoo sounded like The Assembly sounded like Erasure (with exception of the featured artists, or course)...I hope you get my point.