There is nothing wrong with needing a mobillity skill vs trapcastles. Each kind of castle should require different tactics, skills and to a certain extent equipment.
The problem is that atm there is no other choice but to use trap castles because everything else is bugged, exploitable or underpowered. And thus you are forced to bring your mobillity skill because every castle you attack is a trap castle.
With the ticket system using more then a handfull of creatures becomes very easy to be exploited by an attacker because they can aggro all the mobs and either run to the bossroom or the entrance. There they can safely kill all the really dangerous monsters because with the ticket system, of all the aggrod monsters only a few will be active and attacking you. Traps always work and don't start fleeing because of one to many aggrod snotter.
With the current upgrade system half your creatures will always be underlevelled and useless because one AoE can take them out before they can even do anything leaving only a very few creatures viable. Traps don't die from AoE
Then there is the fact that except for headshot Zekes no creatures can deal with ranged heros which means people have to negate the advantage of being ranger and kiting-> traps.
If more setups become viable you will see less of these kinds of castles and more variety.
Like said, different castle setups should require different tactics and I am perfectly fine with certain obstacles requiring specific skills to effectively deal with them. Try and succeed or fail, learn and adapt.