I'll have to say that only one person has been harping on the definition of Gran Turismo, so don't paint with
too broad a brush.
Frankly, I'm with the bikers on that one. The reason being that the Gran Turismo series, rather than being defined by the classic automotive term, is all about motorsports. And... by golly, motorsports includes bikes and bike racing.
However. One thing the bike fiends should keep in mind is that yes, modeling one vehicle means that another vehicle
isn't being modeled. Note that for every truck, SUV, dinkmobile, hybrid, dragster, rocket car, etc that's being included in GT5 means that some other vehicle is going to be left out. Hopefully relegated to DLC in the not-too-distant future. PAPPACLART talks as if the modelers and coders can sit around and say to each other, "We have an afternoon break coming, why don't we create five motorcycles instead of goofing off?" It doesn't work like that. It's quite a lengthy, testing/tweaking intensive project to get a vehicle to perform in a fairly realistic way across a variety of racing envelopes. Just one.
Now, maybe part of the secrecy surrounding GT5 is that indeed, Tourist Trophy Mode and a nice selection of motorcycles are going to be included. Maybe there's an entire Polyphony II section with their own employees and networked superstations working on getting the bikes and racing modes included. Okay, if that's what happens, I suppose we both will be happy.
However. Yes, I guess I'm getting a little carried away with that drama thing.

But this isn't a small matter. You do realize that in order to have this, that GT5 is going to be a compromised game. It's going to be a little bit Gran Turismo, a little bit Tourist Trophy. Something will be left out in order to wedgie these two games together, and both would be larger, more complete games if they were done separately.
But... maybe I'm wrong. Maybe the laser scanning and physics work which was ongoing since the days of GT4 and TT have been put to work efficiently over the last four plus years. Maybe we'll actually get two games in one, with no loss of much of anything. 700 - 100 cars, 50 - 200 motorcycles, 75 - 100 race courses. I do know that Kazunori-dono isn't going to settle for anything less than a quantum jump over GT4, and most racing games in general. So if we do see bikes in GT5, it's going to be because nothing suffered because of it.