Because you're so pacifistic in Dead Island, right? The Left 4 Dead games are action horror shooters. Leaving aside the several strategies that involve running past things without killing them - and indeed, the finer details of how not killing things can actively be better than killing them - killing everything is what you do. A game's focus being simpler does not inherently make it any less challenging.
follow the directions in the 100% linear levels.
'Kay, well, first things first, the levels aren't 100% linear. There are several that have branching paths (The Parish, Swamp Fever, No Mercy) and all of them allow for different strategies used in beating the finales, as well as in navigating the environments, provided the areas are large enough.
Not sure what you mean here - are you referring to the fact that the levels themselves are linear, or that indications such as "Start the Concert" will pop up? Both, neither?
- In the case of the former, linearity does not mean that a level is easy, especially if you're playing on expert, or realism, or both.
- In the case of the latter, it's mostly a matter of making people know how to do the finale events. It's one thing to get overrun by zombies, but quite a frustrating other to have that happen without even knowing what you're supposed to do. It's simple, yes, and arguably hand-holding, but - I really cannot stress this enough - it doesn't make the levels any easier.
DI = Watch out for your stamina,
Except that you can beat almost every single combat encounter in the entire game by mashing the kick button, which requires no stamina conservation whatsoever.
Except that Left 4 Dead 2 introduced a stamina mechanic in order to combat a similar problem in Left 4 Dead.
Except that both Left 4 Dead games have run speed mechanics (>40 health points is a speed reduction, 1 health point is a much more severe reduction) that work similarly to Dead Island's sprinting mechanics.
I assume you mean keep
track of your ammunition? Yeah, Left 4 Dead has that. 'Cause, y'know, it has guns. Which use bullets.
Perhaps you're talking about the pistols which have infinite ammo? Decent point, but they're craptacular unless you get knocked down (which is bad) or against much anything meatier than common infected.
I mentioned this earlier, but a significant part of the metagame in Left 4 Dead is knowing when to run past everything and when not to run past. Because the special infected (boomer, hunters, etc.) can only spawn four at a time, and can't have four grabbers at a time, you can guess what special infected will pop in next and how much of a threat that means given the current situation.
it's far from survival horror but not as twitchy or direct and linear as l4d.
Left 4 Dead is definitely twitchier than Dead Island, but I'm really not seeing how that - or being more linear, or more "direct," whatever that means - means that it requires less strategy.