Somewhat related with the MUL and it's relationship with new players (we frequently get a lot of new players in our group).....
I always thought it would be a good idea to have "starter army packs" like the boxes GW has (at least for Alpha strike), to help new players. Each box could have 8 mechs with variants chosen to add up to 250 points (roughly the same value as each side of the Starter Set), with the printed Alpha Strike cards included (make all the boxes the same era), a copy of the quick start Alpha strike rulebook from the Starter set, and a set of faction dice. For example a DCMS box could include a Wasp, Jenner, Panther, Wolverine, Catapult, Dragon, Lancelot, and Katana. Start with the five major houses, and if those sell well add a couple Clan Starters too. It would make it easy for a new player to pick a faction and have a good collection of iconic mechs that are usable in most eras.
Catalyst wouldn't even need to make new sculpts, and if you could sell a box for about 60 USD I think it would make onboarding to the game much easier for new players. No messing around with the MUL and combing through bunches of variants or what not. Just open up the box, read the rules, and play a game. It would be great to be able to point out a Fed Suns army box for a new player who is interested in them as their faction. I think the army sets would also sell pretty well to experienced players who want to start a new faction up.
I find the MUL is much more manageable to use once you have played a few games and are a bit more familiar with stuff. I know the guy who is kind of the ring leader of our community has a 200 point army for each of the five great houses that use pretty iconic units to that house and when new players come he just says "pick the one that you like the mechs the best in," and then grabs another one and plays a demo game with them. That method had me playing Lyrans as my first faction, as I liked their iconic mechs the best. After playing a few games and becoming more familiar with some of the mechs (I was already familiar with some of the common mechs as I played the HBS game), the MUL became a lot more easy to navigate.