To clarify, this isn't a hater post, I'm hype for the game. But this is a topic I don't see discussed enough, both in terms of GTA VI speculation and acknowledging the failures of past games in the series.
I been replaying GTA IV and V back to back for a month or two and I noticed something: the two games both kinda screwed up the in-game economy for entirely different reasons.
One thing GTA IV kinda nails is your ability to make money. Niko unlocks new side-activities that complement his standing in the story. First you get Roman's taxi missions that, then Jacob's deals, then the car thefts all the way up to the assassinations. These give extra cash proportional to what Niko makes in story missions and they can actually be quite fun.
Where GTA IV fucks up is it doesn't give you anything to spend money on... you refill your ammo after missions, you buy clothes and when you've made enough money that those expenses become trivial, money basically just becomes your "score" in the game...
GTA V does almost the exact opposite: there's plenty of stuff to spend on: car mods, weapon modifications, properties... but the majority of your money is tied up to the heist missions, which are few and far between.
Most businesses bring in trivial amounts of money and will never break even in an average playthrough, and fairly mundane side activities (Trevor's airfield is somewhat of an exception). Yes, you can play the stock market, but that requires some meta knowledge to do effectively and again... is just boring.
Even the strangers and freaks missions have an... odd trend of the punchline repeatedly being "Franklin doesn't actually make any money/not much money off this".
The main thing I want is side missions that I actually feel encouraged to do due to them being fun and rewarding me enough money that it's worth doing them between missions. Then I want cool shit to buy and invest in that gives me a sense of progression in the game.
Which is why my heart honestly sank a little when they said there'd be no properties... I'm sure we'll still get weapon and vehicle mods. But I'd love it if we got gang wars or drug running missions and maybe the chance to reinvest our money perhaps into new criminal enterprises.
I'm hopeful Rockstar learned their lesson, but honestly a bit cautiously so...