If this was a Perfect World(tm) we would not have a text buffer at all. Unfortunately the text box is still a neccessary evil, as voice comms are still not quite there yet, though getting closer. However, I still believe there are 3 things that makes a great sim: immersion, immersion, immersion. A text box with scrolling messages telling me what's wrong with my plane or that "xxx" killed "yyy" kind of blows the immersion for me. Same reason I always have the HUD stuff turned off. You can tell what's wrong with your plane mostly by looking at your gages or by looking at your wings or back to see if your smoking or not or by how your plane is flying.
I also don't need a million kill messages flying by when I am trying to read messages from my squad. Now I know everyone has their own ideas/tastes so I would suggest that customization is the best policy. IOW have filters that work on the FE's sim to the '.ignore' command. How bout a series of switches that sets what you see in your text buffer: select from No System Messages; Your Kill/Killed Messages; Your Squads Kill/Killed Messages; Your Country's Kill/Killed Messages; All System Messages. That way everyone would have what they wanted.
Another thing I would like to see(especially if I had No System Messages turned on) is a sortie debrief or summary after each sortie. It would come up like your score when you are in the tower(or whatever), but show what plane you flew, who you killed and what plane they flew, what ground targets you destroyed, how many rounds of ammo you used, if you landed/bailed/killed, etc for the last sortie just flown. And with a button that lets me save the info, or an automatic save, with a new file name each time like 'sortie1.txt','sortie2.txt', etc. That would be real helpful for squads like us that keep track of statistics on squad nights, as well as looking at my own statistics over a night.