Difficulty.

@dragofire202Yes, this is one of the many things that needs to be changed about current ops (IMHO). Because, as of currently it's way too easy and doesn't offer any challenge unless your facing spooky squash.
Many other things I think need to be changed about ops.
Rework of Elite bosses: 90% of them are the exact same thing and are too easy.
Adding an option for more waves: 5 long waves feels much more boring than 10 short waves, and aswell as that there are less bonus waves and overall just less satisfaction.
Making it so the large amount of coins accumulates over time as apposed to just giving you a large amount for defeating a boss.
Being able to summon AI to help you in solo ops: Why was this feature removed? It was so convenient to have in Gw2 because of how much freedom you were given of having another ally at your service.

I could write a lot more, but I wont bother for now.