I think 10|5 is a little too slow for blitz, and a little too fast for standard. That's probably why it's not implemented, they don't know which category to put it into.
Add 10 | 5 to default time controls in live chess

Thanks for the comment. There has to be a dividing line somewhere. Even Daniel Rensch has played a similar time control during live sessions to get better competition (many strong players don't play standard) and give the audience quality chess. Besides, I'm sure it's based on some mathematical formula since if you create a custom time control the server places you in the appropriate section. All I'm asking for is a predefined entry in the list so its a bit easier to get a game going.
Of course I concede that if you have 100 entries in the list then it's pointless.

10|5 is available now as one of the default choices.
I'm not seeing it - is it going to roll out slowly? (Like some other upgrades have done?) Right now, when I click "new game" and then the drop-down menu for the time control, the rapid defaults are "10 min", "30 min", and "more". Even if I click "more", 10+5 isn't one of the options.
One of my favorite time controls is 10 | 5 which falls in the category of blitz. I like it because you get more time to think vs the 5 | 2 time control and you can play some higher quality chess, still keep it in the realm of blitz, and the increment allows you to save a winning position when you are losing on time (unlike 10 | 0).
I think it would be great if you could add this option to drop down list in Live chess. I know you can create your own customized time control but it can be difficult to get a game going with non-default time controls because people simply aren't searching for that game. However, if it was available I think you would see a lot of people making the switch from 10 | 0 or 5 | 2.
Thanks for your consideration.