This very question is something that's been eating at me this entire riding season. I have a ten year old steel framed road bike that I ride all the time. I also have a Vespa 250 that I use for my daily commute and a mid to late '90's Felt RXC pro that I've adapted for commuting, so my motorcycle has seen comparatively little use. The sad thing is that it's a brand new Tiger 800 that I've had less than a year. I've ridden sport bikes all my life, except for time off taken after my daughter was first born. Motorcycles are addictive but they don't make a whole lot of sense. Even a very utilitarian bike like my Tiger is still pretty specialized. As daily riders, the Vespa and Felt are at least as useful as the Tiger and more pleasant to ride, and the Tiger is a GREAT bike.
So, the thought that's been going through my mind as I ride my road bike is selling the Triumph and using the funds for a new road bike. I still can't bring myself to sell the Triumph but it's probably just a matter of a couple of years before it's gone. In the meantime, I'm going to start test riding new road bikes this week to see if there's anything I'm truly missing.