I don't feel that it's good UI to have a dropdown menu that requires scrolling to see all of it (i.e. the menu itself is a scrollable panel). What about using toolbar-style icons, with helpful explanations on hover? (Unfortunately I don't know how you translate hover to touchscreen devices, but who really does serious wiki editing on a tiny phone screen?)
Topic on Talk:Edit Review Improvements/New filters for edit review
The menu is already subdivided, if you take access to Namespaces and Tags into account.
A toolbar would have been less efficient on the discovery side. Imagine that you have a very new interface you see for the first time, and you have to hover every icon to know what is done by each button? This is why everything is descriptive, with a title and a description.
And if you know what you are looking for (because you are an experienced user), you can still use the search bar (the blue highlight area here).
Concerning mobile, I would say that desktop editing is a "developed countries" privilege. So it would be unfair to have "serious wiki editing" only done on desktop. This is why mobile users now have a specific design for their Watchlist (see this week Tech News), which helps them to monitor their favorite pages with a better access to the filters.