I don't think I'd enjoy any of those old favourites now, though. A few years ago a friend gave me a joystick with several C64 games built in, including fondly remembered Paradroid and Iridium. It wasn't a great experience. Many things are better left as (sometimes inaccurate) memories.
I have less patience these days if part of a game seems unfairly hard. I like a challenging game if it doesn't seem unfair (Full Metal Furies being a recent new example I've played, which coincidentally is retro-inspired).
I have less patience these days for bad design, which sometimes makes things 'unfairly hard'. A lot of older games suffer with bad design compared to games today, but that's often because the medium has progressed. Some games were ahead of their time. I mentioned a few old games in my opening post that I enjoy to this day, and one I'd never played before (They Stole a Million, a strategy game).
Games seem less playable using a joystick to me too, perhaps because I got used to a controller pad. Playing using keys is still fun.
Retro games and pixel art is huge at the moment. I think that's largely due to nostalgia but also because designers have learnt from the past, so the games of today tend not to have the flaws of those that inspired them. The 16-bit era was the best for me in that many of the best games (e.g. Super Mario World, Sonic 2, Super Probotector/Contra III, Terranigma, Donkey Kong Country 2) are as playable as the best games today.
Downwell is the best new example of 8-bit-style graphics I've played:
It's outstanding, and the trailer doesn't do it justice. Also difficult, but not unfairly so. And it gives you the option to play vertically if you can rotate your TV/monitor.