In the past, alt+enter was the only way to add a break before a table (see Depends On). Now you can press enter at the very first position and get the break before. So this shortcut is obsolete (and probably also the command).
I do not agree. I see no reason for this. No benefit in removing it. It's already in use and some might use it. And it's similar to MSO.
I have to agree with Timu - I use this shortcut daily, irrespective of their being a table in my document or not. Please do not remove it, hide it, or otherwise depreciate it.
(In reply to Alex Thurgood from comment #2)
> I have to agree with Timu - I use this shortcut daily, irrespective of their
> being a table in my document or not.
I tested it, but I can't see, that there is any function outside a table.
No, can't remove it. The shortcut 'KEY_RETURN | KEY_MOD2' shortcut  is in EditWin for both 'NoNum' non-numbered paragraph, and for 'SpecialInsert' for text insertion before or after a table or section .
And as the SpecialInsert is applicable to both Tables and to Sections its shortcut can not be removed.
Also, the <Alt>+<Enter> SpecialInsert action inserts a non-formatted paragraph, while the <Enter> action at Start of Table incorrectly inserts a Text Body formatted paragraph.
I didn't know this shortcut. Indeed it is very usefull.
When I needed a line before a table in a new document I always cut the table, press Enter after that paste the table.
I guess it's safe to close this.
Should someone come with new argument and action, feel free to set Unconfirmed.