I have been converted! I've been against putting in some sort of skip mechanic for a while, as the order of the levels is very important. Skipping a couple of early laser levels for example, a player would miss the lessons and techniques those levels teach, and would then be frustrated by laser levels using those techniques. Soon, they'd be skipping all the difficult laser levels, which is about half the levels in the game.
However, playtesting has revealed that some players do get stuck on one particular level for an inordinate amount of time, and don't know what they should be doing differently. If this happened on the same levels, we'd look at changing them (and we have changed many 'pain-point' levels in the past that proved too hard or were otherwise tripping people up!), but the levels players get 'stuck' on varies quite a bit.
So, we're putting in a 'limited skip system.' The player will be able to skip a small number of levels, but to skip more they must go back and complete a level they previously skipped.
This should solve the problem with getting 'stuck,' without allowing players to completely bypass a mechanic and run into later problems.