a) People need to get over their fear of multiclassing. You can build your character however you choose. Having a few levels in one class and a few levels in another class doesn't make them any more or less those classes than you with your 14 levels in a class. You both made valid character creation choices and should be happy with what you did.
b) People aren't nearly as selective, exclusive (i.e. *****y) as you'd think from coming to these boards. I've never ever seen anyone go "Oh, no don't invite him, we don't need a
full rogue, find someone with only 2 levels of rogue instead." or anything even remotely similar to that. Most of the time, people just get invited to groups. Sure, to a degree, people tend to feel like they have to have a healer and a tank, but that's generally about it.
c) Rogues do way more than disarm traps and open locks. So stop looking to those two things to make your feel like you have a valid and useful character. So long as you think those are the only two things you bring to the party you'll always be disappointed. Quests should
not be designed to require someone to disarm traps and/or open locks. Just like they shouldn't be designed to require any other specific classes. Adding optional chests behind traps and/or locks is the best thing the devs can do on this level to encourage the inclusion of rogues.
d) All of the above said, Rogues sure could use a few specific changes to the game.
- A way to sneak attack undead and/or constructs. This could be a feat, an enhancement or a magic weapon; it doesn't really matter much.
- More skills. And more (powerful) uses for existing skills.
- The ability to take any bonus feat in place of their 10th-level+ special abilities.
- Real prestige classes.