I know the Spellscale's Blood Quickening ability can grant you temporary feats for a day, including limited-use metamagic feats, but would this make it worth forgoing the actual feats themselves?
The Spellscale’s racial abilities are another consideration for your choice of feats, but they do not, themselves, make other metamagic feats pointless.
Metamagic is kind of awkward in 3.5. Most metamagic feats, including all of those that the Spellscale can get, cost more than they’re usually worth: they might occasionally be worthwhile (particularly high-power ones like Quicken Spell), but they’re too costly to use all the time and the regular spells of the heightened spell level are better.
So a spellcaster focusing on metamagic has to do something about that, by investing “metamagic reducers,” options (mostly feats) that make metamagic cost less.1 But because you have to invest resources in making your metamagic usable, now you want to be able to use it all the time. Blood Quickening is useless for this, and a Spellscale metamagic specialist probably wouldn’t bother with the meditations that grant Metamagic feats at all, since they would take the good ones themselves.
Ironically, Quicken Blood is better for Spellscales who aren’t using much metamagic: they might have a decent one available in one of those cases where it’s useful, without burning a full-time feat on it.
1 Metamagic reducers can very quickly lead to absurd amounts of power. For example, enervation is a classic spell for this, and it’s quite possible to be handing out a dozen or more negative levels per turn with stuff like Quicken Spell, Split Ray, Empower Spell, etc. etc. So really focusing on metamagic should be considered a fairly high-optimization tactic that is not appropriate for every table (though it can probably be used in moderation at many tables).
Considering that Empower and Improved Counterspell are the most useful (in combat sense) feats of those available via Blood Quickening, the question is whether you want to focus on metamagic or not. If yes, then Blood Quickening won't be enough and you should take actual feats (and metamagic cost reducers, and metamagic rods, and whatnot). If no, then Blood Quickening is a nice ability that will cover all of your metamagic need except maybe Extend.