Disc games can be bought second hand and can of course be sold on if you don't want to keep them. Can't do that with digital. So, you might possibly save in the long run if you have the disc option.
Furthermore, not every disc game gets a digital release. Most of the 'big' games do, but if you have a taste beyond the AAA titles, or if you want to import games from other regions that aren't available in the UK or on the UK Playstation Store, then, again, you might want that disc option.
I'm a collector, so I like getting games on discs anyway.
I've had every PS console at launch since the PS2, and launch versions ALWAYS have design faults and problems. For that reason I'm going to wait for the second or third models of the 'phat' PS5 (but before the inevitable Slim). Most launch titles are usually pretty average, too. I'm happy to let others be the beta testers this time!
My main issue with the PS5 is the cost of the controller. That's the problem with having all these hi-tech features - they drive the costs up without really adding much beyond gameplay gimmicks. I'd love for Sony to release a simpler version of the controller that I can buy as my Player 3 and 4 controllers for party-type and sports games.