AAVV: "But remember, small gunners can't use flamers and the game shouldn't encourage making sporeplant killer-alts like that."
Look at this problem from other side. Does have the game adapt to every individual player's character, or do the player's chars adapt to game?
In your example of smallgunner that he is not able to kill sporeplants... he have the choice: he can invest some skill points to BG skill (even little, because flame thrower dont need high skill) and then he would be able to mine (scanvege there). He needs to adopt to the game mechanism, not oposite.
The consequence of this, is minimize of mininng (scavenging) alts. How? If you want to mine (scavenge) res (items) in every locations, you have to first create alt with enough skill points in needed skills. If i.e. one resource place needs small guns, lockpick, other big guns, doctor (to heal sporeplants poison wounds..), you are not able to create dozens of mining alts only by simple registration, you would need to level each one char to adequate level (because even more HP are needed for higher tiier mining/scavenging).
Numerical cooldown should be replaced by "gameplay cooldown".
This time equal to level up your mining char = kind of cooldown time, single investition, also (in my view of path is the destination) portion of fun.
Well known current cooldowns could be eliminated and replaced by "fake cooldowns", by time you need to get adequate stuff, time needed to move to res (scav.) location, time to get thru "dungeon", time to mine (find) res. (stuff) and time to leave back to base (city). Because there should be still some threat (respawning beasts you kill, lower ammo,...), you would be limited in some way of mining.
But i agree, that as a player, you should have more choices than one. So even you would not create special mining or scavenging alt (and please, there are a lot of people, in factions maybe majority, that think that creating, balancing and using special purpose alts for special situations is very popular part of fonline .. for the PvP, for PVE .. so this alternative is not necessary evil, as many of you thinks), you can create and balance your single alt that he would be able to get stuff he would need. Dont tell me, that your small gun char needs acces to locations with res. or parts. needed to craft energy weapons.. why?
And even if you dont want to invest points to all needed mining (scavenging) skills, you can invest to one and barter with other players (or join factions). And even if you dont want to barter with players, you can barter with NPCs.. Or you can PK... Or you can beg for stuff...
So there is a lot of possibilities, depends on you which choice you choose (harder, easier). I disagree with idea, that solitaire players should have same game difficulty than multiplayers. This is multiplayer game, and as in real world ... just read The Wealth of Nations from Adam Smith. If you choose solitaire gameplay, you have so specialize and barter with others.
RANDOMNES: Yes!, But! .. i think that devs forget their roles of game mechanics scripters, directors and let everything on dozen of years old game mechanism. Critters have HP and damage, players have HP and damage, who have more wins. This game has much more potential in scripting of some situations that could bring more entertatinig gameplay.
I.e.: mining place full of ants, constantly respawning, so even with zilion ammo you cannot kill them all and mine (scav.) some resource. So what to do? Use flares, put them on ground and set up light borders, because ants are afraid of lights and until flares are burning, you are safe...
So yes, randomnes.. i.e. in conditions, when flares would be burned (1-3 minutes), randomnes in paths or obstacles in tunnels (sometimes you would need to use dynamite,..), but not randomnes in the way, that easiest way to mine is avenger build with a lot of ammo to kill all kind of critters (because does not matter what kind of critter is randomly spawned (from rat to floater), you can everything killed by most powerfull weapons).
Well, dont tell me, that you dont like this and you want rather counting until 5 minutes cooldown is done. :/