It seems arbitrary to me. Why put some equipment on the main interface and not others?
Good point - and it was something that occurred to me - which is why I suggested a number of allocated slots - that way the player can decide which items appear in the HUd dependent on their own personal preferences and gameplay style
It can be confusing.
Short answer: Nah
Long answer: If anyone finds the HUD in its present incarnation the slightest bit confusing then perhaps they should be graduating kindergarten before playing computr game like this - alternatively show them the considerably more complex XCOM HUD and they can thank their lucky stars how much more simple and streamlined the current HUD is.
Furthermore, even with these slots, what happens when you don't have a hand free for the items in them?
They are greyed out / unavailable in exactly the same way that a two handed primary weapon becomes unavailable / greyed out of the player equips something with the left hand - so no change to fundamental gameplay or interface required
One option is to put your weapon in your backpack, another is to drop it onto the floor. The game can't know which one is preferred, as this changes according to the situation. For example, there might be space in the backpack, but only after rearranging the things that are already in there.
So basically what I'm saying that while a change like this might ease operation for the player, it will likely introduce more problems for being complex.
Think of them as shortcuts to simple common actions and I think you might start to see what I'm driving at.
I originally envisaged this as a quicker simpler way of selecting and using different grenade types - (later in the game I generally carry 3 or 4 types) - so what happens after you use it is irrelevant in the respect you are talking about - it gets rolled or lobbed then goes boom.
In terms of other items that will remain in hand after use like medikits and secondary weapons, there's a number of ways this can be dealt with - all of which either simplify operation or don't make any difference.
for example with a medikit or 2ndary weapon, once it has been equipped and used there could perhaps be an option in the popup menu from the crosshair that says "drop" and another that says "return" - that way the player can perform either of his preferred options without having to access the equip screen - alternatively they can do nothing and the item remains in hand - result: operation simplified.
Alternatively the player can access the equip screen and do it manually - result: no change to this operation but the overall operation of equipping, using and returning/dropping the item is simplied.
In the situation where a player needs to use an item not shown in one of the HUD shortcuts then they use the equip screen as normal - result: no change to this operation.
Finally there is no mandatory demand for a player who chooses not to use them to use them at all - they are just shortcuts after all.
Either way during battle gameplay the trade-off is in favour of the player with only very minimal additional complexity.
Outside of battle it does an an additional planning element for the player - they must decide which items are most likely to come into play during a particular battle scenario and where best to equip them for best use - while this does make the initial pre-battle equipping stage a little more complicated, this kind of thing is something that a lot of players will positively enjoy this as an additional management feature.
Do you have any other concerns or objections?