We have a wood burning fireplace, and when we first moved here, I didn't notice it bothering me all that much. I could have bought glass doors for it then, but I didn't see the need.
Well, the last several years, it has bothered me (and even when it's not burning, and is scooped out) year around until I got in there and cleaned it out good with the vacuum hose, and did all the nooks and crannies well. And then I discovered that, due to the age of my fireplace, the glass doors were no longer available from the fireplace manufacturer, and since it is an odd sized opening, we will have to have custom doors made (and they are twice the price of the original doors I should have gone ahead and bought! Gah!).
So now I have a 9 pillar candle holder with glass candle holders and votives. It looks really pretty, and gives off a little bit of heat too, lol, that will have to do until I stumble across my fireplace doors somewhere, or manage to splurge on the custom doors.
So, IMHO, if you can get doors that fit your fireplace now, go ahead and spring for them. Even if it isn't bothering you now, it might later, and then you will be stuck like me (and my dh loves a real fire- I feel kinda bad about that, too <img src="i/expressions/face-icon-small-sad.gif" border="0"> ).