All these games are abstractions, so any discussion of reality should be thrown out the windows.  Very rarely are battles fought against evenly matched opponents, with units who start at full strength on both sides.  That is why you have command level staff, to find the point where your opponent is weak and strike it with as much force as possible without exposing your weaker areas to your opponent.  I would argue also a game based on reality wouldn’t be much fun, since there are just way to many variables to remove the abstraction.

So back to the original question.  Yes I believe the tanks should be there.  Why?  I am a big proponent of give me options to play the game I want to play, not be pigeonholed into a game the designers think I should play.  I will be happy to have a spirited debate on what subjectively is fun or not in a particular game.  In addition if the OP and I were to arrange a game, it would be more than fair to discuss and decide what type of game we wanted to play and put in limits between us.  The goal is an always to have fun, and since it is a shared experience, not just me but all parties have fun.

Tournament Organizers do it all the time.  They change the rules of the game to make the tournament “fun” for the participants.  Being limiting unit types, changing point values, changing the build rules, etc.  For some people the fun in gaming the system…how do I build the best bag of units within these rules.

While I take exception to the OPs argument should tanks be a part of bolt action, or similar games.  Note: not the part that the OP said that the set would not be fun to play, that is a subjective thing and completely valid.  At a certain point things do need to move from an in game unit to a set piece.  An Imperial II Stardestroyer in a game of X-Wing for example is a point where the thing becomes a set piece just because of scale differences.  An AT-AT in Legion would be very close to that edge, again in my subjective opinion.  I still think it would be fun to have rules for both though, since it opens game opportunities.  A coop version of X-Wing against a Stardestroyer might be fun.

–Chris