[General Questions and Answers] juzten:
This is all opinion based. But reasonable opinions.

The Devs here at XDA arnt disappearing or doing any less developing for the majority. Instead the number of devices and different variants of those devices are growing so rapidly, that it lessens the probability of you obtaining a device that a Dev feels passionate about, and puts time into developing.

Also, technology advances rapidly. A mod that changes your status bar can quickly be abandoned due to capability issues in the next android version.

Dev's dont recieve a lot of monetary gain, or proper thanks or appreciation for doing what they do. Android is a very complex machine. Multiple layers, multiple languages, and unique in that design. Very complex, with scripts that have calls for this, and calls for that, which has to be constructed correctly to pull from any section, under any circumstance.

New android releases have ability to duplicate and sometimes enhance, with the combination of a launcher, those features of a custom rom. Which causes less people to have reason to need or want a custom rom.

The cell phone companies would probably love to give customers the freedom of unlocking boot loaders and rooting phones with ease. Think about it. Samsung has a year warranty on cell phones.. you root and you have now voided that warranty. They no longer fix your device for free. Also, if they helped you easily achieve root on your device then they gave you, the customer, what you wanted, without risk of being responsible and in the same token, made you a happy customer. Its the carrier companies you should be angry with. They are the ones who puts money into Samsungs pockets. I mean have you ever purchased a device directly from Samsung? Or did you obtain it through a carrier company? Almost all individuals originally get cell phones from carrier companies. That being said - if verizon puts a clause into the contract that promises Samsung they will buy so many devices for so many years, only if they will increase security and difficulty of getting super user access, which will decrease the chances of a average customer removing that device from Verizons carrier lock. Samsung isnt going to decline a major carrier. Its not only verizon. Its most carriers. How do you think they profit from selling a 200$ phone for 20$?

Now heres the good things happening in the cell phone world..

Its now mandated that all US carriers provide free unlocking, from the network carrier lock, on all GSM devices sold after a certain date. Granted you meet all the stipulations they require. So now greater freedom of phones, or at least a law, made by the US government helping customers fight big companies. When we all know, its not too often that happens.

Anyone can root any device. As long as you know the languages android is designed in. Its all open sourced. You can compile and build an exact replica of your phone, except a few parts. The problem is in the difficulty of doing that. The complexity slows progression of released one click roots, or flashable roots.. those were programmed by people or teams who put in hard work to simplify the process to increase the chances of average people to successfully root.. those people are the Devs your talking about vanishing..

Another big thing ive heard about. The new android 8.0 Oreo has made the process of building custom roms, more simplified. Basically making the construction of one phone, be the same construction of multiple devices and variants, making roms free from being device specific. Increasing the probability of you owning a device with the same build as a Dev thats releasing a rom. Reversing what i said at the start of this reply. This would also cut down on the need to port, and decrease rom bugs like audio and wifi or volte. Thats what my understanding of it is. If im incorrect about this please someone explain it better, in lamans terms..

All in all, I agree with your statement that less and less rom development is happening. But, I feel like that is about to change directions. Not headed back to the way it was, but a new path.. and im ready for it..

And try apex launcher. Gives you ability to hide apps even in the free version unlike nova.. pretty sleek and fast.. alot of customization.. that along with a pie app,which gives you almost like a "apps edge" feel.. i also heard about a way to change your quick tiles in newer android versions.. the only thing about that is, im not sure if they were talking about just changing the main tiles at the top or changing them altogether.. i hope altogether.. i never use smart view, or power saver.. instead id like to have pandora, xda labs, etc