Red should be the 2nd color for instant and sorceries but all its playable instant and sorceries are basically burn. Card drawing has seen 1 playable card exactly for now (Faithless looting) and it's mostly a dredge card, while its spell manipulation is basically non-existent outside of overcosted fork effects. Its creature are also worse than blue's ones, and chaos effects suck/are overcosted. LD is dead so it doesn't even have that form of disruption anymore, and the best LD spells isn't playable anymore anyway (Cryoclasm). The best red card of the last 10 years is Pyromancer and that's because it's abusable in blue decks, not red ones. The 2nd one is probably Lavamancer. I like a lot the artifact theme, but that's basically dead too, since outside commander decks, the last things that favored artifacts in red were in Urza block, with some semi-playable in Mirrodin.
Green has still more permanent removal, enchantment matters theme, ramp, and actually good LD (mnwovuli acid-moss), plus decent card drawing engines (lybrary, Glimpse, elves, courser etc...) and tutors (GSZ, Survival, Commune, Pod etc..). Its only flaw is the stack, but that's totally fine for a color that don't focus on spellcasting at all. If anything green could get more fight effects on creatures and playable spells because that's supposed to be green form of removal and perfectly in flavor with the color. It also could get more disruption effects for lands/artifact like Root Maze.
Red mages are literally book wizards but can't do anything but create fires. It's as if gandalf only did fireworks. Red should totally have spell blast variants effects, which feel way more red than flashback effects tbh (reminiscing is totally blue, blasting spells should be more red but whatever).
I think you can see the problem the most on PWs. Red one's feel all so similar, while blue and black have some pretty different planeswalkers, and white and green are inbetween.