After that I always had a nice monitor and it really was true. No matter how slow my computer was / is ... having a big screen to use it on makes it a lot easier to tolerate.
I always found it funny how some games were able to handle wide screen with no issues, others much more difficult.
Your computer will change, and has little to know difference on your health.
Your monitor, keyboard, mouse (and chair/desk can also be included) are your long term tools that you use to interact with your computer. They can be a benefit or detriment to your health (eye strain, RSI, back pain). If you have to work with your computer for your job, and do so for many years, it's worth it to purchase tools that have long term benefits.
Good luck finding an LCD with any concrete health benefits beyond any other. The industry literally just adds a bunch of gimmicks each year to see if people bite. All I can say for sure is IPS prevents you from needing to fix your head in one angle (especially for low contrast images), and most LCDs are too bright.
This reminds me of another issue: If you have a monitor with overdrive and use a color temperature adjuster like redshift, the overdrive smearing is often super bright while the rest of the screen is mellow.