It's a little condescending to ask a game producer if he's ever played an FPS and to put his hand on a keyboard. Maybe you should phrase your question, "How many abilities do you expect a player to have access to during combat? Will it be the 50+ that WoW has, or more like 8 that ESO has? How do you plan on mouselook working?"
Personally I like the 50+ option with the caveat that many of those are situationally useful abilities.
As stated it turned into more of a rant rather than a question.
With that being said, condescending or not it's a topic that needs to come up, (obviously in a more softly worded diplomatic manner) as apparently nobody designing these games has ever played a FPS or looked at a keyboard. Otherwise, of all the wannabe action mmo games how the fuck is Cryptic Studios and their steaming pile of McFreemium dogshit ie neverwinter the only game to get it right? I don't even wanna know how many tens of millions if not more that the Wildstar team blew through building that game without a single designer taking 2 seconds and looking down at their keyboard, but that's exactly what happened.
It really comes down to a basic question which from what we've seen they've already answered. Is the combat going to be "action" based or hotbar based. Does movement and positioning (and even potentially targetting if they opt for reticle vs tab target system) matter, or does GCD monitoring rotation memorization matter? Again from everything we've seen so far it's going to favor action combat. Telegraphs (whether displayed or not), dodges, positioning, collision, physics, etc. I need to keep this guy in front of me and my back against the wall or he's gonna charge me and knock me into the lava, etc. If he does X i need to counter with Y or i'm gonna be stunned and he's going to get this spell off, etc. I need to watch whats going on on screen and react, not watch one of 6 hot bars for ability #74 to come off cooldown.
If you are going to do action combat it needs to be done right, or not at all. It's really easy to do hotbar combat. With few exceptions almost everyone else does, and the SOP is solid, just copy WoW, like everyone else does. Now if you are going to do action combat you need to stop and take 2 seconds and realize that the hotbar and number of abilities you give players to use is one of those things you need to NOT copy from WoW. Instead you should look at action based games like a FPS. Even 99 vanilla Everquest was more action-y than GW2/WS wannabe action games. It was First person by default, you only had up to 8 abilities (spells) usable at once (though most melee classes only had 2-3 + autoattack), and it's default hotbar was only 1-6, with Shift+1-6 available for more hotkeys. bank 1 being spells 1-4, Shift+2 for bank 2 being spells 5-8. All of those keys readily available without leaving WASD (even though obviously it wasn't needed since you couldn't manually dodge).
8-10 abilities really is the sweet spot, and that's including at least 1 mouse button free'd up from not having to hold down right click the entire time you are playing because mouselook isn't default always on. Do you need 5-10 buffs and clickies? either they are meaningless fluff in which case no, just include them in the default balance of the class, or they make or break combat in which case you autolose any fight in which you don't initiate and you are not prepared for.
There's a simple design concept in aviation (i'm military, previously worked on fighters, now i'm somewhat on the other side piloting drones) called HOTAS. Hands on Throttle and Steering. If you've ever seen inside the cockpit of an airplane you'll know that modern aircraft have about 1k switches and toggles and various assorted systems and functions in the cockpit. Modern fighter jets are the same, except that every single switch or the functionality of every switch which is necessary for combat is available without the pilot's hands leaving either the throttle or the stick. And neither one of those 2 things have as many buttons on them as that naga mouse linked.
An action combat mmo, especially a pvp centric action combat MMO needs to have a similar design philosophy behind it. WASD is throttle and your mouse is the stick. Yeah i've played enough badly designed games that I can reach over and hit 9 or = on my keyboard and quickly revert back to wasd but why the fuck should I have to do that? With 16 archetypes so far, i'd rather each having a handful of straight dmg abilities and a handful of special abilities with distinct animations that I can recognize and react to, in order to counter, rather than staring at a hotbar waiting for something to light up and react or heaven forbid, clicking it, in order to counter. In an action combat game I shouldn't have more abilities than keys I can comfortably reach from the WASD position and, more importantly, the default key bindings for those abilities should be those keys I can reach from WASD. FFS don't make them 1-0 because reasons. Idk, I guess cus WoW did it.
Slyas buy a fucking naga bro
Don't even get me started on the (abomination of) gaming mouses like the ones you linked. If your game requires having to thumb dial on a goddamn telephone of a mouse in order to play properly your game is not an action mmo. It's a gcd monitoring watch for flashing lights whack a mole hotbar game. And that's fine if that's what you are going for. There are plenty of rote pattern memorization games like that where everything is balanced on gcd activations per cycle and a mouse like that is the only way to improve your efficiency. But that's not what this game seems like it's going to be about, at least not from what they've shown us in pre-alpha videos so far.