HOA responsibility

Is the HOA responsible for repair and maintanence of front doors to units, or are they the responsibilty of the individual home owners. I live in a four unit townhouse complex and the CC&R's only address glass doors and windows and does not specify front doors. ARe they part of the "structure?"

Are you in a HOA, Condo Association, or managed property? I am also NOT clear with about the responsibility of your windows/glass doors. That information may lead to a clearer answer.
If you are in a Condo or Managed property, then it is possible for the exterior doors to be their responsibility. Often Condo's or Managed Property can run like apartment complexes, with Exterior/Interior maintenance availability. Say a water pipe breaks in a SHARED wall of your townhouse/condo, most likely the Condo/management company will send someone in to fix it. The repairs could go against their insurance company. They are responsible for the overall structure of the building.
If you in a HOA situation, then you most likely are responsible. However, here is the "catch". You may NOT be able to replace it with just any door you want. You may have to have the door APPROVED by the board/ACC committee since it is something seen from the EXTERIOR. If you put the door up WITHOUT approval, the HOA can remove it at YOUR cost. You still pay for the door no matter what.
In our HOA, doors can NOT have glass and must be solid wood/steel. The color must be approved as well. Can't have a bright neon green door if no one else has one!
So find out what kind of management scheme your under. Do you own your own home and they maintain they property around it? (HOA) If a pipe breaks, do they pay for the repairs? (Condo/managed property).

Honestly, I think your confusing the "HOA" as a "They". The HOA is YOU and your neighbors. So when you want your "HOA" to pay for replacing the door, your essenially asking that you and your neighbors ALL chip in together to replace the door.
HOA's budget work much like a "Kitty" in Poker. ALL the poker players put their chips in (dues)and then use that "Pot" to payout to the "winners" or in your case, who needs the repairs.
Now that I know that the glass doors/windows are the homeowner's responsibility then it makes it clearer that your exterior door should be as well.
My suggestion is to replace the door yourself. Otherwise, you leave the door selection up to your neighbors. Do you like your neighbors taste or yours?