Li Shenron
Legend
If yes, then there are several issues with the system that need to be ironed out, in addition to flat-math.
Once again your language makes it sound like a different gamestyle than yours is inferior... Why "if no" then ok, "if yes" then it needs to be fixed?
For instance, what has the rogue been doing for the last 20 levels? Why didn't the wizard memorized Knock 15 levels ago when the locks were a real issue? Why didn't the fighter smack it to pieces? Why didn't the cleric summon something to eat the lock?
And all these are possible reasons why I don't think it's bad for a system to not let everybody pick that lock. You are making it sound a bit like "one way or the other, the PCs are going to win the game, so why bother with the details? just let them pick that lock..."

In my favourite gamestyle, that Rogue at 20th level can certainly pick almost any lock if he bothered to invest in lockpicking. Otherwise maybe the wizard can cast Knock if she chose to learn that spell. Maybe the Cleric cannot summon anything imaginable. Or eventually the fighter can smack it, and this is very probable unless he shouldn't break it for some reason (avoiding noise, wanting to put it back like it was, maybe the lock is not on a door but on a box and smashing would destroy the box...) but there are also games where even that 20th level Fighter isn't always a Hulk with uber Strength, and weapon skills won't help him break the lock with brute strength.
All these alternatives are fun for me when they work, but they are also fun when you don't have them covered and you have to find even another way. I prefer a game where it's your choice to make your PC learn these stuff, or learn something else. I won't say that it's badwrongfun if someone else likes a game where every Rogue has lockpicking, every Wizard has Knock, every Fighter has 25 Strength at some point, every Cleric can summon anything he needs... I'm saying, once again, that my own favourite style is that there is always a choice, and you can never be really good at everything. I do not like a rules systems that assumes everybody (or the party as a whole) will find a way to be good at everything so let's just make them good at everything by default. I'm fine if you like it, so be fine if I like something else.