It's only a problem if you choose the ISU commnader. There are several other commanders that gives you direct strikes. I think the balance team made it very clear the reason for that change You can't have a perfect commander that deals with everything. And Remember the commanders that LeFH(ost) belongs too aren't as powerful as the ones that ML-20(though that's no reason for ML20 to be shit though) belongs. GRCA is a very strong commander that everyone has access.
Storm is still pretty good at everything. It's awfully muni-dependent but still really good.
The slightly lower accuracy on the ML-20 means it loses most of the time to the LEFH. It is almost never worth building and generally a poor choice compared to getting another Katy. The LEFH is much more viable.
The ML20 used to be good when it had a huge AOE and much fewer shells. Relic greatly increased the number of shells in one patch, then quickly nerfed the AOE, making it much more RNG dependent than it used to be.
I'm not sure how much I would want the ML-20 buffed. I stopped playing 4v4 randoms as allied about a week ago after a streak of around a dozen games when my teammates built 6-7 arty pieces. I'd sometimes see people build 3 priests or Sextons, then wonder why they get crushed at about 45 minutes.