Castelli and others produce shorts made for professional cyclists, who do long rides too.
You know where I see more room for improvement? Winter cycling gear. There's a huge difference between good stuff and shitty stuff. Example: Milano Sanremo a few years ago when it was snowing, and lots of riders were riding with non-team issue Castelli Gabba jerseys because they're one of the best things going for cold weather racing.
I guess that's not a problem for you in Singapore, but here in Italy, winters can get cold and wet.
I don't know... Italian cycling clothing manufacturers are the best in the world (which is why you source from them), and I'm just not seeing a compelling reason to go with someone else.
You might look at Rapha - they've managed to carve out a niche despite not being from a traditional cycling nation.