I have that quad core i7 Mac Mini, to which I went from 4GB to 16 for maybe $50 and I added a second SSD hard drive inside with a $10 kit. It is an awesome machine, and a shame that Apple downgraded the mini into a weak little box that can’t be tinkered with at all, just as it did with MacBook Pro. At least with MacBook Pro, they can claim what they did was necessary to make it sleek and lightweight. The mini is the same size and weight as before, but my model from 2012 is still way more powerful than any dual core i5 model is today. And I got it for around $600.
However, good news for those who like the MacMini, if you are a little bit technically proficient: You can make your own. I made a quad core i5 Mac with 16GB of ram and an SSD hard drive for around $500. Go to this site: https://www.tonymacx86.com/. Buy the system you want, from a corei3 mini to a beast of a core i7 that equals the Mac Pro. After buying, follow the installation guide and you can have a great computer. On mine, I also have a second SSD on which I run Windows, and the software allows very simple booting to whichever OS you want to run.
So despair not, mini lovers!
Love my mac mini. I bought it 2 years ago and a super drive to go with it. Tiny footprint in my office and it always works. It's all this old guy needs.
Models such as yours are plentiful on eBay for under $300. I just looked. :-)
I use a Mac Mini to control my 32 channel sound board and do the mixing in real-time for live performances. It works like a dream. Probably the best Mac ever made IMO for all the reasons you cite.