War is physics, small arms are responsible for 2-3% of casualties, over 50% is from HE, which has risen in that modern warfare seems to be to just drive about in armored trucks and get hit by IED's. In the future, the fact that you'll have spacecraft to pelt the world from above with any objects of your choosing ... conventional forces are more useful in a limited engagement. A big suit of armor, or giant stompy robot, seem to have all the limitations of tanks: can't walk down a hallway, too heavy for floors, etc; w/o many of the advantages. It would be weird to think of the e-tool it would need. Flying can be of dubious value, esp considering a combat environment that has lasers as ADA.