Try flying a Turtle in a asteroid field and you will find it becomes easy prey to lighter capitals.
Rheinland has nothing cometitive in cruiser class. The LABC is stronger and even has 2 BS slots, the siegecruiser is very smal and very agile with one realy dangerouse maingun.
When you compare houseforces you have to compare everything, you may not picking out one candy and then demand you want one as good as that aswell.
Factions are meant to live with theyr special RP including theyr hardware. Thats what makes it a different challenge for a different Faction and thats what the Game should be.