Is is just coincidence that we have had two doctors 10 and 11 both regenerate durring christmas specials ?. Christmas can be an emotional time of year. Both good and bad feelings are stirred as we celebrate with family and freinds. You also can't help but miss people who you have lost who are not there to celebrate. If Claras exit is at christmas and well done could be a real tearjerker. 12 and Clara need to see eachother one last time.
Say goodbye properly no secrets or lies. That way they will both be free to move on with their lives.

Yeah, it was done that way so that the new series would have a new Doctor.

Personally I'm not a big fan of all of these Christmas exits. It's a relatively important aspect of the show, and begins to feel totally at odds with the feel of a Christmas episode.

Tennant's exit is the perfect example. They were aiming for a big, important, classic-status story that was quite bleak and/or serious in places, and so the sentimental, lighter, mainstream elements that are par for the course with a Christmas episode begin to feel very jarring.

I'd much rather have exits in the series main, it's more impactful, and would show consequences of big-event finales a lot more. The odd Christmas farewell is fine, but mostly those episodes should just be a bit of fun, not too boggled down in the comings and goings of the leads (especially the 'goings').

Clara has to be given a dignified exit.
I want Clara to stay but IF she goes, she should die doing something heroic.

Oh good God I hope not! I'm not just saying this because I like Clara but because quite frankly I'm getting really sick of these "tragic and forced out" companion exits, it's getting so old now IMO.

Why can't she just leave with her head held up high and in dignity through her own choice and on good terms with Doc 12 just like what Martha did with Doc 10?

Yes agree completely.

Agree as well.

Personally I'd rather we didn't have Christmas episodes at all and the extra budget was used to extend the main series.

i agree. xmas episodes tend to be pretty awful by anyones standards.

Tennants doctor did not regenerate in the Christmas special. End of time part 2 was broadcast on new years day.