For hardcore keyboardists, portability usually comes as a second priority, although it is important. The most important are the sounds and features +/- touch. Despite our complains about weight etc, we're still happy to lug around stacks of modules and heavy keyboards if necessary. During my earlier days, I've brought large and heavy stuffs all over the island - even if that meant getting a taxi to Sentosa and setting up my gig for a short 20 minute section with group of chamber strings (just to make sure that I produce the right sound). It was painful, I complained a lot, but at the end of the day, the satisfication came from getting the "right sound" and people peeking over my shoulders staring at all the lights blinking my from modules and effects unit...
Anyhow, those days are over for me and perhaps for others, now that we can get more with software-based solutions.
So back to the subject - 88 keys are really OK, particularly for keyboardists with piano background.