Your game should use as few pieces as possible, and they should be the standard game pieces.
If you don't understand this, a publisher will teach it to you the hard way, when they insist you cut down your game, or, far more likely, just reject it outright.
Minimising components isn't as important as fun, simplicity, or other matters, but it's certainly next on the list. You should be considering it as you design your game.
You're also giving your players, who don't have infinite money, more value for their money.
It's a big cost for a publisher to print vast quantities of components. Do you really need all those dice in the game? Does each player need to have a separate deck? Can that deck be half the size, and still work the same? Does the board need to be huge?
Always try to make your game with standard components. Almost all games can be done this way, and still look great.
Standard pieces are regular dice (4-20 sided dice are fairly standard too), simple coloured wooden bits (various cubes, discs, men), punchboard (thick cardboard for boards, chits, and other flat pieces), and cards.
Things like custom dice (dice with faces that aren't numbers), and unusual resource tokens (fancy resource shapes, animal shapes) are still mostly acceptable.
Miniatures and other custom-moulded plastic pieces are very expensive.
It's not the amount of art that goes into your game, it's the amount of unique art that goes into the game. Most cards in your decks should exist as multiple copies of the same card. There should be a few rarer cards that only exist as singles, but most cards should be doubles or triples.
A deck of cards you draw from, during the game, can't be double-sided. Most other things can.
Boards, chits, and cards not in decks, can all have a second side. This is a great way to fit everything onto less components, or add variation.
If you have two things that don't work well together, or do something very similar, you can just put them on opposite sides of the same component, so they can never both be in the game at the same time.
Make sure that all components are being used regularly. Do not include components that are only occasionally used.
Every component in the game must be entirely necessary.