Worse! At just level 7, a rogue is likely to have +11 and Advantage to pick a lock, which combined with Reliable Talent means they can't fail a DC 21, and have a 1/2 chance of beating a DC 26.

So if you want there to be uncertainty and challenge, you have to make the DC more like 25-28. Making it all the more likely that the lock should be impossible to the rest of the party.

If I wanted to formally add ability check crits I would make them add/subtract something from your result. Not automatically pass/fail, because the consequences of that are bonkers.