Frankly you can almost solo-tank Syrcus Tower, that's what. That's just how it was designed. Forcing a second tank in per party would have just slowed parties down and placed an extra three people who would've been basically bored and useless into each party. LotA at least has enough adds flying around, party splitting, etc. for 6 tanks to sort of make sense.
I agree that it's not quite ideal, but I can also understand it - it can be tough enough to design to provide for three tanks in a single fight, regardless of scale. Nevermind six. I think Syrcus being one-tank only is a realisation of that among things they learned while designing CT.
