I don't understand... How can people prefer complicated web pages with fancy design over the simple and effective design of your router configuration page?
I mean, look at it... It's beautiful. If I ever asked as a client to a developer to build me a website, it'd look just like this.

You are going more into the realm of Ui/ux what is simple and beautiful to you might not be simple and intuitive to someone else.
Now, I know what that is. You know what that is. But if I see a website looking all 90's as fuck in 2019 I am going to think that
a) its a phishing scam
b) its probably a shit service if they can't afford good design.

And also, fancy looking does not mean overcomplicated. That might just be your take my dude. But i do get your point(not disagreeing with you or anything)

@AleCx04 Totally agree. A fair example would be the UI of most of the cloud infrastructure companies, (Google Cloud, AWS, Azure etc.), which are simple, intuitive and data driven.

We are replacing those style of linksys switches left and right.

Forget the ugly ass UI.. it's hard to automate any UI. That's why we get switches with a true cli

I threw up a little, but I'll be fine once I can work through this UI trauma with an experienced therapist.

It seems backends, from routers to automotive OEM applications, prefer to look simple and 90s. But, as @AleCx04 mentioned, it's unlikely anyone will take a frontend seriously if it looks like that.
So if you were to ask me, I'd say go simple for enterprise or "power user" interfaces, but keep it shiny for the general public. Simple interfaces keeps development costs down anyway.

@ajit555 absolutely. I had something like that in mind. For what op showed does make sense, but i can't nor could i really convince myself of running a service on a different kind of application that looks like that.

Can you imagine the amazon store with a similar user interface? Hells naw

@AleCx04 I see your point. If I saw a website like this even I would question its credibility. It's a consequence of the fact that we associate a good site with another type of design.

It doesn't matter that much how fancy looking a design is. The UI design must conform to standards and guidelines so that people in general can use it. There are quite some techniques to achieve this, such as defining personas and for each persona, make sure the UI design meets their needs. Also a simple method like card sorting can help in creating logical menus, categories etc. Of course, one should use common sense and keep the industry one is designing for in mind.

Not conforming to guidelines and standards or not thinking about personas will lead to (at least some) users not finding your web app user friendly and maybe even not (or stop) using it, no matter how fancy the design is.

I own quite some websites and even have 1 that hasn't been updated for 10 years,.so the design looks a bit old fashioned, yet this is the website with most users and highest conversion!

The UI in discussion is an Admin page. The attached UI is as modern as an Admin page can be.

Yeah...something like that but a little less 1996. I can't really praise the whole repetitive flat minimal simple shape designs of recent either. It's getting old and kinda saps the personality out of a product/service. I feel like game UIs do a great job and many designers can take away from that.

There is a use case for everything.

That password tab needs some serious padding 😰

Ew