Battery capacity is a seriously difficult intertwined chemistry/physics problem. There's still a ton of unknown things going on in a battery.
Believe me, considering the payoff, a lot of companies and R&D people are working on it.
That's why you see all the super-hyped "researchers discover new superbattery" news articles where it always says "should go into production in 5-10 years" (i.e. never) and you never hear about it again.
Edit: my feeling is that people should work on making current batteries cheaper (which is what Musk is doing with the Gigafactory) which will make electric compete with gas, and then that will drive more demand for charging station infrastructure.
My electric bike cost US$18K and 85% of that was the battery. It's a hell of a performance machine and I do actually get 80+ miles out of it going 70mph, which is great considering how un-aerodynamic a person on a motorcycle is. It should cost $12K max though, to compete with gas.
My FJR takes $16 in gas every 2 weeks. My SR takes about $1.20 in electricity to go the same distance and I don't have to search for hippie-free non-ethanol gas.