It goes to the point. The important part is whether you can make the check at all, not necessarily whether or not you get a 10% bonus to that check. In this edition you can always try, and with good stats you are likely to succeed. There's no 'untrained' penalty. There's no downside to 'not getting' a skill.
Except there is the line in the description of the lock piece of equipment, "Without the key, a creature proficient with thieves' tools can pick this lock with a successful DC 15 Dexterity check". That leads me to believe that if you are not proficient with thieves' tools you can not attempt to pick the lock.
I honestly wish that line was not there as I prefer to let everyone try if they want, but that seems to limit some tasks to only those proficient in the skill or tool.