The point that a tank can be blown up is not senseless, it is concise and to the point. Distance is the best armor. "Give me a fast ship, for I mean to go in harm's way." JP Jones.
Or as my brother (Maj. US Army) puts it, speed is life.
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Armor detracts from fast. Yes, you can supercharge the engine, but that leads to overheating. There is no free lunch.
EVERYTHING'S a trade-off, there is no do-it-all vehicle, plane, ship or weapon.
If these knuckleheads were around in 1942, they would be telling us the F4F Wildcat needs to LOSE its armor so it can maneuver better with the Zero. Problem is that though the Zero could out-turn and out-climb the Wildcat, you only had to breathe on it to knock it out of the sky, and it couldn't dive worth a crap. It also did not have self-sealing fuel tanks so it would burn like a comet from a dirty look. In fact if it got in a dive much over 360 mph, the stabilizers became useless. Wildcat pilots could often just go into a steep dive to escape.
Say again, everything is a trade-off...
I agree that it is a trade.
The other important thing is TACTICS, so that you can use your strengths, and cover your weaknesses. Our soldiers and marines are very good at that, as shown by the loss ratios.
Our soldier's body armor helps, the armored vehicles help, but no Hummer is going to shrug off an RPG hit. The good news is that our soldiers use automatic fire, and the RPG is single shot. Our tactics encourage the enemy to take a shot at the limit of his range with a single shot weapon that is most likely to miss, and we answer with mass fires either by several automatic weapons, or by large caliber rounds. We also look carefully for changes, knowing that each additional piece of garbage can be cover for an IED.
Next: small robotic sensor-gun packages that can manipulate battlefield debris, but are armed, so the enemy can not ignore them. Just the thing to investigate the new pieces of garbage before our guys get within the casualty radius.