A problem I've been seeing an increase in the past decade or so is an increase in overspecialization. The end result has been "graphic artists" under the DELUSION they are designers when they don't know enough about HTML, CSS, or accessibility to hand a front-end coder what they need. Back end coders who don't know enough HTML/CSS/JS to slice up what the front end coders hand them, or the knowledge to recognize when what the front-end guy handed them is junk.
Worst of all are the front end coders who know nothing of actual design OR the back-end so they are incapable of keeping the artist inline, or to hand the back-end people what they need.
Everyone in the process should have at least a general knowledge of what the others they're working with NEED, as well as the things that should be avoided due to screwing over some other part of the process.
If all you know how to do is spank it on the screen in a paint program like Photoshop, you're not a designer no matter how pretty the result. If all you know how to do is slice up images and slop it together with HTML/CSS frameworks, your not competent at front-end development no matter if the result looks like what the artist handed you. If you don't know how your HTML and CSS is going to be split up, how to develop to leverage caching models to the best, and so forth you aren't going to be giving people on the back end what they should have... and really if you're working on the back end where the result is being shown on a website, if you say "Well I don't really know HTML we have a front-end person for that" then you have ZERO blasted business using any server-side language for that task.
This becomes evident whenever you see someone slopping the STYLE tag and STYLE attributes all over the place, using presentational classes, presentational markup, or crapping out bloated graphics heavy pages that tell users with accessibility needs to go plow themselves!
Basically as the front end developer you have ONE job. ONE FLIPPING JOB!!! Take the data -- CONTENT!!! -- and to present it to the user in as accessible, useful, and speedy a manner as possible. Knowledge of how the data is stored, can be accessed, and how it is processed can greatly improve your ability to do this.
To paraphrase the Vulture, (Red Baron to you normies): "Find the data and deliver it to users, anything else is rubbish!"
Admittedly, I just had it out with a marketing director who keeps insisting they need to spice up the pages we're working on to "Draw in the users" -- It's a banking portal where people access their accounts; if the user is there YOU ALREADY WON THAT FIGHT!!!