Actually I don’t think you need to highlight, the caret just needs to be anywhere inside the word—that is how it works for me anyway. If you aren’t currently typing anywhere near the word, then the mouse can come in handy to get the caret there—but from that point on, it’s still faster to Ctrl-Cmd-D with the hand that didn’t leave the keyboard to use the mouse. That is what I took to mean by “it needs two hands”, I don’t think they meant it takes two hands to type in the shortcut. It seems a moot point to me, since the left hand isn’t doing anything anyway if you use the right hand to do the whole point-click-seek_menu-click thing, instead of point-click-shortcut.
Hmm, setting up a new Dictionary shortcut in system preferences only works for me if I highlight the word, while Ctl-Cmd-D works anywhere within, or immediately adjacent to, the word with no highlightinq required. So I’m left wondering, what are you doing differently?
Also, on this, once you have the cmd-ctrl-D bubble up, if you do need more information beyond what’s in the bubble, you just click on “More” and it brings up the full dictionary for you - and this is still less work than using the contextual, even the 1.x one.
And as has been pointed out, if you really do prefer using the mouse and use this a lot, just place the new dictionary icon in the toolbar (View > Customize Toolbar…) and click on that - it has exactly the same effect as the item in the ctrl-click menu and will be faster and easier to get to.
So, if this is indeed about efficiently getting to a feature you use a lot, you are clearly not lacking in choices! Cmd-ctrl-D and then clicking “More” if you need it (which I doubt will be often, but it’s there if so); setting up a keyboard shortcut in System Preferences to bring up the full dictionary whenever you need it (it doesn’t have to be ctrl-cmd-D - you can remap any keyboard shortcut you like, whichever you will find most efficient); or using the toolbar icon.
If it’s just about something changing that you were used to, well, I understand that as we all have our habits, but this has changed and with the other, much more efficient, options readily available, it makes no sense to change it back when it will just lead to clutter in the contextual menu. The arguments about this being inefficient or a backwards step don’t really hold water given that the submenu in the contextual menu is there for sporadic use by users ctrl-clicking to find things - the contextual menu, that is, provides the expected tools for those who call it up in the hope of looking something up or checking a spelling and so on, and provides access to other Scrivener-specific features the user may not have been aware of. But the contextual menu is not as efficient - and never has been or will be - as keyboard shortcuts or toolbar clicks for features you use dozens of times a day.
All the best,