The whole issue of bandwidth boils down to signal-to-noise ratio. To boost S/N, you can do a combination of large antenna and high transmitter power. The higher the gain from the antenna, the greater the pointing accuracy requirements. The greater the transmitter power, the greater the need for electrical power, volume, and heat removal. Of the two, going with a bigger antenna might be the easier solution. There are some folding antenna designs that are pretty big without weighing a lot. Pointing accuracy increases, but that's a pretty mature technology, especially given the high orbital altitude that reduces slew rates.

For the mass of 1 MTO, I believe you can build several smaller satellites that would have a higher net capability. It's true that you probably wouldn't be able to get the same bandwidth from a single smaller satellite that you could get from the MTO. However, you could probably get much better navigational accuracy (very useful for lander and rover operations) and you'd have better overall redundancy. Even if a single smaller satellite only was able to achieve 25% of MTO's total bandwidth (and I think you might be able to do better than that), that's a lot more than you'll get when the sole MTO dies. Further, with a simple crosslink capability, you could have 24/7 coverage if necessary, something that isn't possible with a single MTO.

Everything is a tradeoff. In no way am I unhappy with MTO. Personally, I'd prefer my approach, or I'd like more than one MTO. However, with the ever present budget constraints, I think multiple smaller satellites would've been a better solution than a single MTO for the same price. Sometimes, a very capable system can be built in a small package, like the XSS-11 set for launch next week. That's the microsat I described yesterday, featuring high data rate transmission, streaming video, autonomonous operations and rendezvous, a 1 year life, and a mass of 100 KG (much of that being propellant).