Why punish people for changing classes?

I agree with what you said.
You should be able to swith classes freely inside your spawn.

If you are worried about bots and juice, instead of refunding the money, upgrade the skills in the same quadrants of the new class. That way people can switch classes to adapt to situations.

a green posted about this in a very old thread regarding the same issue. ie some classes farm faster than others, you'll have to use the search function

So penalize everyone because a handful might slightly abuse it? If you get screwed by enemy snipers and can't move 2 feet as a heavy class, just suck it up or start from scratch because a handful might "abuse" a few extra dollars in farming. Ridiculous.

Indeed.

One could start out as a high money gain class and switch to their main.

You're assuming everyone else sees it that way
It may have been suggested to let people return to spawn to change classes, but I don't think anyone has asked that all money spent on upgrades get refunded as well

Being able to return to spawn change classes and get your money refunded doesn't work in this game because of upgrades and how juice is acquired.

I could start as assassin, do the early juice, take down the turrets, go back to spawn change to tank and escort bots safely tanks to charge 3 and the product grenade.

It works in TF2 because there are no actual resources you have to control (points and carts don't count).

i think its the lack of dlc

Some might abuse it? I know for sure that this would happen in every game at least half is try-harding. Of course, not everybody is try-harding, but genarally speaken, when one starts try-harding, others follow.

I understand that you want to be able to change your class if you get anhilated by your counter, but I find that one can get his money back, since then counters don't actually exist anymore. Because when you get killed by someone who is supposed to kill you, you can change kill him, followed up by him changing and it starts all over again. This would make the assault more powerful since there is no actual counter for him.

Gunners are the counter to Assaults...

Only if the assault wants to die.

Not if I jump your *** first.