Agree on the damage. The point in D&D is to reduce some attribute of the enemy to zero before they reduce one of yours. Sometimes that's a single spell. Sometimes you attack HP, sometimes abilities, etc.
Warmages = versatility. If you focus on something else (like, say, hyping one spell) you're far better off being a sorcerer. You aren't a laser, you're a swiss army knife. Adding more attachments is always good.
I do think Warmage Edge loses its usefulness after the early levels - you'd much rather (if you had a choice) pump the heck out of your CHA and let the INT linger. At low levels, a high-int, low-CHA warmage is plain murder. Those gray elves throwing the cantrips at near 10 hp damage are sick sick sick.
Arcane Spellsurge, like Celerity abuse, is exactly what you SHOULD be doing. It optimizes your options. Let the sorcerers Arcane Thesis. They can one-trick pony it. You need to have lots of tricks. Any of the dips that don't cost you too many caster levels and nets you spells from any list should consider that one (Recaster, Wyrm Wizard, Lyric Thaumaturge, etc.).
- Actions: Celerity, Arcane Spellsurge, etc. Options are good for everyone. Since you're not specializing in a "thing", specialize in being very efficient.
- Universal Damage Applicability: Sanctified One of Kord, Paragnostic Apostle, etc. ... you have enough spells that are save base, touch base, SR/not that you can find one that should apply to each target ... but making the damage bypass resistance is key.
- Multi-targeting: Born of Three Thunders, esp. if you have a daze-immune solution and are also doing Celerity ... this allows you to attack a different attribute than HP ... shotgun approach but now you can attack HP and multiple saves. And you can do it at any point in time as long as you have a spell slot open.
Other spells that have huge payback in options:
- Alter Self, Polymorph, Shapechange ... grab the ability you need
- Summon (whatever) ... summon or call the ability you need
- Anyspell (incidentially, does anyspell count as the ability to prepare spells?)
Basically with those you can respond to any situation appropriately. No sitting around to re-memorize spells. The key is to maximize your options. This is why Malconvoker is a good PrC ... it focuses on the summons. For any particular job, you can probably get a good or appropriate tool through a summons. Shadowcasters. It's why wish and miracle are such awesome spells. Yeah, you can do neat stuff with them ... but the fact you can mimic any spell with them is pretty darn useful. Anyspell.
This is what you turn your Warmage into. Not a Malconvoker ... but someone who, on any given round, has a number of things they can draw from spontaneously to hopefully solve the problem. I don't like super-specialized casters ... because then you get into the situation where if every tool you have is a hammer, every problem looks like a nail.