So what you're saying, if I'm reading this right, is that when push comes to shove realism is more important than fun? If you had to choose between a dull and uninteresting chokepoint meatgrinder of an encounter and "wahoo!, epic cartoon fantasy" you'd choose the former?
While it may not be fun for you, can you at least leave room for people that find "more realistic" fights as more fun than "epic cartoon fantasy" fights?
To many people, using the world in intuitive ways makes for a fun game (it adds to their immersion, lets them act in a reliable world, etc.). So, using a chokepoint to slow enemy progress and limit their advance and your own danger
is fun, not "dull and uninteresting."
Again, it's cool if you don't like it, but can't you see that "more realistic" is more fun to a lot of people, for various reasons?
Also, what if you like that sort of thing? What if your bag of tea really is "wahoo!, epic cartoon fantasy"? Should D&D just leave you out in the cold because this is a serious historical re-enactment game?
No, it shouldn't. It shouldn't force it the other way, either. I think this issue already got nailed, though: it boils down to the CaW vs. CaS argument. The best way to make both sides happy is probably to give "good" advice on encounter design: if you want your party not to use doorways every time, give them a reason to act differently. That is, make damaging terrain in the center of the room that they'd need to push enemies into, or maybe the enemies will knock a table over and fire arrows/throw spears (so you need to plow past the fortification and get to them, in the center of the room), or whatever.
But, it makes sense to use doorways, and it should make sense in-game, too. Why wouldn't it? Of course, the enemies could always not engage them, content to throw oil/light it on fire, move out of line of sight, go for reinforcements, set off traps, or whatever. If they don't have these things available to them, then it makes sense for the party to exploit their weaknesses, much as they'd use fire against creatures with vulnerability to fire. And, if you don't like their weaknesses being exploited, it's back to CaW vs. CaS, and you should make sure encounters encourage open-field fighting.
At least, that's my take on it. I don't think there's a good way to get around the doorway issue. You can give your Fighter a Whirlwind Attack ability, but if the party decides that staying in the doorway is better for resource management (through saving HP that would be lost from open-field fighting), then they're just going to stay in the doorway anyways (unless there's a reason not to, such as saving hostages, escaping quickly, using terrain, etc.). As always, play what you like
