I find that sorcerers easily match wizards in spell casting oomph (not in DUELING, not by a long shot, but that is another kettle entirely), but do lack somewhat in the 'uniqueness' or flavor department.
To fix that, I use the variant that Frukathka mentioned (except I use 1/10 gp cost), plus the option to conduct a 'Ritual of Blood Bonding' to sort of absorb a focus component into themselves (or 'attune themselves to the mystical energies within the focus, so that they can use their own bodies as the focus yadda yadda...').
Basically, pay 500 gp times spell level or 100 times the cost of the focus, whichever higher, plus 25 XP per spell level or 5 times the cost of the focus in XP, whichever higher, and you never need to use that focus for that spell again. This may seem a lot, but it really isn't: 25 x 9 = 225 XP which is
way cheap for removing the focus component of a spell. For really expensive focus components, you can just continue to use the focus.
I also give a sorcerer a wizard's bonus feats, 4 skill points per level and most Cha-based skills as class skills -- I do think that WotC overcompensated a bit on this one.
The end result is that a sorcerer, with the right feats and rituals, increasingly approaches an innate spellcasting creature, while the wizard uses sympathic magic (material components) and other mystical mumbo jumbo to achieve the same effect.
Finally, instead of the very weak dragon-bloodline theory, sorcerers IMC claim to follow the 'Greater Path' of magic, ala the Tsurani black-robed mages in Raymond E Feist's Magican: Apprentice, Magician: Master and other books of the Riftwar Saga series. You might be surprised to learn how much of the antipathy sorcerers recieve is simply due to a lack of inspiring fantasy 'rolemodels'. Once my players identified Pug and Macros as the archtype for sorcerers -- wresting raw power from the cosmos itself, taming and molding it with sheer will and discipline, while the 'lesser mages' putter about with their rats tails and bat droppings -- they took to the sorcerer class
much more enthusiastically.
Basically, the sorcerer becomes more 'cool' while the wizards becomes simply 'nerdy'.
Anyways, I think much of the reason sorcerers are less popular in D&D has to do with the fact that D&D fantasy emphasis wizard types over sorcerers (Elminister, Rastilin etc). That is only natural, since the Sorcerer did not exist in AD&D. However, a DM that can weave the sorcerer into his campaign setting as an independent force, instead of simply 'wizard-lite', can and will inspire his players to choose and love the sorcerer class.