about the bikes
One of the big, BIG emissions problems causing those bikes to be a major pollution source is that many of them are dirty, poorly serviced 2-strokes - and those which are 4-stroke are still carburettor based with no catalyser. They're emissions monsters despite not using that much fuel.
My 125cc "starter bike" is a 3rd-world-spec Honda, whose sole nods towards modernity are electronic ignition, 4-stroke cycle and a 5-speed shift. It makes an awful smell if you are in even a mildly enclosed area, particularly when on the choke. Very obvious that it's chucking out more noxious crap than even my (14x larger engined) 5-seat car. Now multiply that engine by a few million, and you've got a problem, and maybe the reason that everyone converting to Tata Nanos in India may cause traffic meltdown, but probably NOT killer smog.
However, I still ride it for eco reasons because, in the grand scheme of things, it's a whole lot more efficient as single-person transport. Like, to the tune of 3x better fuel economy. If I step up to a more powerful, easier-starting PGFI + cat model of the same or slightly higher displacement (125->150, say), then my conscience will be clearer still, as it should be nearly as clean - in terms of emissions as a percentage of total exhaust - as a modern car. Or at least, one of an age that I'd be able to afford for the same price as the bike (eg Euro 2 rather than Euro 4... either are better than just "spew whatever the hell you like into the air"). Whilst also putting out a third or less exhaust anyway (and saving me bags of cash at the pump).
BTW if your 250cc motor is putting out 11hp, you need to get it tuned - that's what my 125 produces. It's just about right for scooting around the city, with the machine's modest kerb weight pegging the PWR about the same as an 80s city car, though the legal max (for learner class) of 14hp would be more comfortable and make it more viable for longer, rural runs also. I'd be quite interested to see how an electric one would perform, as I imagine it'd be like a CVT scooter with less rev lag - after almost a year of riding a geared bike I'm still occasionally stalling starts because of the difficulty of keeping it in the torque band off the line without thrashing it. It'd make things easier as well as cleaner.
The problem would be one of range. For a tank-filling 11 litres of fuel (so, about 10kg), I can go 250 miles, and though the engine itself is a cast-iron lump it's still only maybe 25 kilos including transmission and oil. I can't see, say, 30kg of battery (and a 5kg, sprocketed motor) giving anywhere near that range, even on an efficient 2-wheeler. 300kg in an only 1/3rd as efficient car struggles to get over 100 miles, and I can easily exceed that in a day if there's a lot of things to be done (to & from work, go drop things off at my dad's place, pick up shopping from a couple of different spots, etc). Yes, you could make the battery a structural element, problem is that's not a new idea on bikes - the fuel tank often does similar anyway.
I'd be interested to see that "250cc" electric race bike of yours, see how heavy it was, whether it was still within the same power class as its competition, and crucially how long those races were. I'll bet they weren't enduros. Any electric bikes I've seen offered for sale - at least, at prices that don't cause hysterical laughter - have terrible power outputs AND short range. Like, 2 horsepower, and 25 miles. I'd be late for work and then get stranded coming home. There are some which can do a perfectly acceptable 50-60mph and cover 45+ miles... but they're a touch heavy, still include crank-pedals for human boosting (or crawling home on a flat battery, as you can't exactly wheel it to a filling station and quickly dump in a few litres), and run to many thousands of pounds. That's superbike kind of money. Not going to be affordable by people who are either using it as a net money-saving venture (like myself), or because they simply haven't got enough ready cash to buy a car (like most of the heavily-polluted 3rd world places - they can't even afford modern fossil-powered bikes, for heaven's sake).
Not really hypocrites, you know. Just limited by funds and technology. It will get better, but you have to give these things time. Consider the history of ICEs themselves - they were rubbish for about the first 30-40 years.