Nairou said:
… using crappy programmer art to get the game functional and playable before looking to find artists to make it look appealing … people doing the opposite, people who are artists first or know someone, and they get the look of the game settled before making the game playable. And I can see why: they immediately have something to post and show people, starting the marketing machine early.
They do both, and it depends on many specifics.
Games in environments that need a pitch need something to pitch. For some games that means piles of concept art, lots of beautiful drawings that convey what is needed for the pitch. For some games that means a tech demo, enough of a single concept implemented to demonstrate the mechanic even if it isn't beautiful or polished or complete. For some games, you need more than the single concept in a tech demo, you need a bigger proof of concept for the entire game created, with a bigger exploration of the concept than a tech demo. For some games that means a vertical slice, a complete playable level including somewhat polished graphics and animations and sound and menus and gameplay and functionality. Once the pitch is made you will need to iterate repeatedly to reach a finished state.
Similarly for games that need a marketing direction, you need something to market. Repeat all the potential different things you may need, you may need to have previously done market research or allow marketing to do it and bring in results. You will need numbers for cost estimates, numbers for business plans, numbers for sales estimates. You will need to iterate repeatedly to reach a finished state.
For games where you are trying to reach a key demo, or publishers, or early access, or whatever else, they all have different needs.
If you're trying to experiment with game design ideas, you need enough to explore the design. If you're trying to experiment with different emotional styles, you need enough to do that instead.
There is no universal answer. Figure out what you need, figure out the order you need to do it, which is unique to your project, and follow your own route.