While 30-meter tall battlemechs are, realistically speaking, "artillery practice", 7 to 10 meter-tall battlemechs are rather more practical for the following reasons:
1) Broken and hilly terrain. I am given to understand that tanks, and tankers, hate broken and hilly terrain.
2) Changing the load-out for a tank is generally either impossible, very difficult, or only trivial changes are possible. Changing the loud-out for a battlemech is, theoretically at least, no more difficult than changing the loud-out for an infantry soldier.
3) At 7-10 meters, a battlemech would not be much less "stealthy" than a tank, and can, theoretically, take the same sorts of obscured positions as infantry soldiers.
4) Hands can be surprisingly useful.
5) Grenades and other thrown bombs. Tanks are generally not also "instant mortar platforms".
6) Theoretically, at least, a brain-machine interface or more mechanical interface makes it difficult to create a more intuitive and easy-to-understand interfacecontrol scheme.