Wait, so including features that don't immediately appeal to the average user necessarily means there will be nothing that appeals to the average user?
I think it's pretty clear the OP's point was only in reference to the Terminal app, not Ubuntu in general. It's a valid point and doesn't really deserve the snark in your last sentence.
I think it's pretty clear that the OPs point was that there was a terminal app on the phone and therefore it was a geek phone that's never going to take off, and that my snark was absolutely appropriate.
In fact he specifically said "I fail to see how this will make the Ubuntu Phone more appealing to the average user." shortly followed by "my point was that this will remain a niche phone."
-Edit to remove somewhat unnecessary snark-
I don't think 'your logic is broken there somewhere' is all that snarky in the grand scheme of things, in fact it's a pretty clear statement of fact. The two things "terminal apps are not appealing to average users" and "this phone will remain niche" are absolutely not logically connected.
I would argue that a good terminal app can help make something easier to use for both technical and average users alike.
Since you can assume that the terminal will be never or very rarely used by average users you can make the advanced functionality available as command line applications and leave the most basic/common options in the GUI.
A naive user is far more likely to check a box and click apply by accident than they are to type "rm -rf /".
A good example is a modern version of Windows, the control panel is full of options,tabs,checkboxes etc that can do weird stuff to your system and consequently make it harder to use because (until recently with powershell) windows has never had a useful commandline.
Your logic is broken there somewhere.