boo boo

You try playing in a band without a drummer.

And yes that includes drum machines.

In my opinion (im saying this so you dont have to) any instrument can play a equally important role, depending on how its being used...For some bands, the bass is actualy more important than guitar, like in most R&B and funk bands and bands like Red Hot Chili Peppers and Primus, in other bands the drummer can play an equally important role as every other member, like Rush, Tool and The Who for example... Then you have bands like ELP where the role of guitar is demolished almost completely, and instruments like piano, keyboard, organ, moog and mellotron are used in its place.