Most of the sibling comments here are a “get off my lawn” type variety that IMHO are not fully informed by what good UX means. Great design isn’t superficial, in the least. A great user experience is a great user experience... it doesn’t mean compromising because something was hard, and it doesn’t throw away how the product is used or has evolved.
We should be aiming to improve and innovate to be helpful, not stagnate. And improvement means people’s existing needs are considered, not disregarded as many here seem to think.
I don't think anyone disagrees with that. The complaint I am making, is that a lot of UX design is superficial, and done for the wrong reasons. Most of what Mozilla has done is terrible.
They've essentially gutted their browser because they want to be cool like Google.
While I don’t personally know the designers at Mozilla, I’m doubtful that they simply “wanted to be cool like Google” and instead did their own research. I could be wrong but usually work isn’t so arbitrarily done for large products and teams.
Why should the baby be thrown out with the bathwater, just to chase cosmetic trends?
Can you give a compelling technical reason why this would be good for users, without using superficial UX fashionista platitudes?
Just because something isn't "on trend" doesn't mean it is bad. Some of the most important and beloved software has user interfaces that have not changed in decades.
I don't care if a UX designer would be embarrassed to use it in front of other mail clients. Trying to chase trends will usually just leave your software looking dated, anyway.
Unless you're willing to roll up your sleeves and keep existing functionality with your new trendy UX, then don't bother, because deprecating real functionality at the cost of a superficial fashion statement is really egregious and it needs to stop.
Nobody wants their workboots replaced with tennis shoes. And especially not because a UX designer wanting to stroke their ego and make a name for themselves.