that's not the argument. the argument is the following:
definition: a crappy situation is a situation where one side forces a win, a stalemate, or some lead, without much influence by the other side. the situation is crappier as the influence by the other side decreases.
No need to define anything. What you're saying is "It's bad when one side can stop itself from losing". Surely it's the very objective of the game for your side to achieve this. You probably mean that it's bad when this can be done easily and predictably.
if an objective of the game logic is to prevent crappy situations, then dretchlifting should be removed (or something else should be done for the humans). (so if dretchlifting should not be removed, then it's not an objective of the game logic to prevent crappy situations.) the disability for non-advanced grangers to wallwalk is evidence to think that it is an objective of the game logic to prevent crappy situations. however, even without this evidence it's intuitive for a game logic to prevent crappy situations.
You've given no reasoning as to how removing dretchlifting prevents crappy situations, even as you've defined them. You've just asserted it to be true and come to the conclusion that if someone removed it then it would prove that they want the game to be better, but if they don't it's still true that games don't want to be bad.
Surely it's the things that are hard to pull off in games that makes them fun.
that's just not generally true. and fun for who? a couple of "mathematical" (counter-)examples:
- you can start teamkilling dragoons with your granger (it's hard to kill a dragoon with a granger). it may be fun for you, but (1) it's not fun for your teammate (that is, if he doesn't agree with your teamkilling acts), and (2) the humans don't give a shit to your epic teamkilling skills, and they'd rather ask for a challenge, than a teamkilling troll on the alien team.
- you can implement a "hax chessgames for grangers" mod on your server, which basically is about: any granger can start playing a private chess game against a good computer chess player; if the granger wins, then the aliens win the Tremulous game. again, you may laugh due to your win, but most people don't give a shit about your chess skills, and they get frustrated that the game ends because someone pulled off a hard-to-do thing.
Sure, I'll admit that statement isn't true in every way. You can enjoy playing a game because it's easy and you win a lot. Still, it's probably the initial learning period when things didn't come so easy that gets you hooked on the game and if a game fails to challenge you, that can be a very good reason to stop playing it.
Regardless, the point was simply that difficulty matters and that you seem to be ignoring the relative difficulties of dretch-lifting and wallwalking.