There is virtually no reason right now to pick anything for Warlock besides cha blast and shove blast. Everything else you can gain either via optimizing your background and race or via in-game items. Battle Master is another non-example because of how incredibly strong ranged shoves are and the fact that their ranged shove also gets bonus damage (on an ability that will presumably already be generating lots of bonus damage). EK has some convenient abilities but the only major reason to pick it over battle master is because you're trying to make burst damage team and need more spellcasters. Build specialization is only a sacrifice if that build isn't generally superior to the alternatives. And again, on top of these examples there are arrows any accurate archer can use that also offer ranged shoving. I get your point that you can do both at the same time but if you were already planning to abuse bonus action melee shoves and you aren't a Thief then why are you not just optimizing around purely abusing ranged shoves instead? They're a lot safer and their subclass/subchoice investment is almost never at the cost of anything significant unless you're trying to run very particular team arrangements.
Warlock* and Battlemaster work just the same in PnP, and whist good, the other classes don't need free shoving to keep up.
*Apart from Devil's Sight lets you see in magical darkness (unlike darkvision), which is massively powerful combined with the Darkness spell.
