Why? Because racers are VERY conservative. They want to WIN. They'd rather race with what they KNOW than try something new. That's the main reason BMW's S1000RR has conventional forks too. There are engineers, tuners and racers all over the grid that know just about everything there is to know about tuning telescopic forks. Racers know EXACTLY how they feel under just about every circumstance.
That's the only thing holding back development. Moto2 was SUPPOSED to encourage chassis and suspension engineers to "go wild" because the engine and the state of tune would be IDENTICAL in every bike on the grid. The only difference between bikes would be the riders and the chassis they were on. So what happened? Basically, everybody is racing a variation of the Honda CBR600RR. Bimota designed a Moto2 bike with their Tesi front end. No one wanted to race it because it was too exotic and unknown.
Damned shame. I do know I've gotten spoiled by my K1200LT's telelever front end. Full suspension compliance even when I'm full hard on the brakes. No nose-diving or bucking around transitioning from brake to throttle either. I can feel the C650GT diving every time I use the brakes hard. Forks have gotten better since my old K100 and R100RT, but they still aren't as good as the telelever.
Maintenance wise, it's better too. Instead of repacking, adjusting or replacing the bearings every 20K miles, you only have to clean, and regrease the ball joints on the telelever every 60K-70K miles. The front shock is generally replaced (or rebuilt if you replaced the stock shock with a rebuildable one) every 24,000 miles, same as the rear shock. The first time the stock Showas wore out, I replaced them with Ohlins shocks. The rear Ohlins was only a little more expensive than the Showa, the front one was more than twice the cost. BUT now every 24,000 miles it only costs a couple of hundred bucks to get them rebuilt, as opposed to spending over $2,000.00 replacing them.