Indeed.
That's just what I was talking about when I imagined Kajiurago being taken away and questioned how long it would take us to want it back.
According to a Russian saying, there are times when the better may become the enemy of the good. Mind you, that doesn't mean that there should be no changes at all - they just should come at their own pace.
On the other hand, Kajiura-sensei started out with a certain style. It's a very flexible style, given her many forays into different genres, so let's take her vocal song style as the best example - violin, Kajiurago chorus, long and dreamy-sounding, etc. She hasn't left this style for years, and shows no signs of making any drastic changes like giru. Although no one has resorted to name-calling, a lot of people here are dissatisfied with her lack of change in both composition and arrangement.
I'd like to add that IMHO Yuki's style did undergo some changes, regardless of how significant we may interpret them as. Observing her OST works as the primary example, it's easy to see that the period from 1996 to 2000 her style can be characterized by using piano and other acoustic stuff for more mellow/gentle/melancholic themes and keyboards for more ominous/mysterious/intense themes (not an exact division, but roughly so). This trend was carried on into 2001-2003, but with the introduction of Yuki's three cornerstones - chorus, flute and violin. The heavily European direction that Noir and Dot Hack OSTs took definitely help to bring more stylistic tweaks and instruments into the fray, plus Noir set the general course for her "techno/operatic" trademark music and Aquarian Age introduced Kajiurago (although it didn't take over until 2004). 2004 in particular was the year when Yuki's OSTs went to employ strings and full orchestra. This is where her modern/classic blend becomes a driving force, arrangements become more ethereal at times and the OSTs start bearing more in common with traditional soundtrack music (YMMV whether it's a good or bad thing
). And I'd say this continued well into 2007. This year has, on one hand, Hokuto no Ken that sounds very traditional (kinda like some of John Williams works), and on the other hand, El Cazador, the last Bee Train collab to date which sounds original even for Kajiura/Mashimo series, dwelling deeply into American music and guitar sound.
Then, the current period starting in 2008. It's marked by Kara no Kyoukai, where Yuki starts making SFX-driven, ambient and slightly psychodelic tracks a prominent part of the OST. These arrangements, along with grim cello and mysterious percussions, were present in her works way before, but only since KnK they have been used distinctively, both in Pandora Hearts and Madoka Magica (and I bet we'll hear more of this in Fate/Zero, too
). Then again, this period also has Achilles to Kame and 15-year-old Soldier OSTs both of which are probably the MOST traditional soundtracks Yuki's ever written.
I think the reason we see Yuki's style as the same is because her "handwriting" as a composer is well-formed and recognizable already. It's not the melodies that are similar to each other, it's their structure - the certain ways of combining different parts and chords into a sequence. It is the same as a writer's habitual choice of words and tropes. Maybe this is what tick many people off, but personally I found this in quite a number of other artist's careers, so I guess that's why I'm more tolerant to it - I just don't consider it abnormal. Also, I don't see Yuki ever abandoning the previous arrangement approaches completely - they are more or less present in each of her works. That's how her overall style sums up.
Experiments? Actually, I think we're better off expecting them in OSTs as well. While the songs Yuki writes generally correspond to the image of the project (See-Saw songs, Saeko Chiba songs, FJ(Y) songs and Kalafina songs all have a different approach to them), I believe it's the OSTs she gets most challenges in, since different plots deal with different settings, moods and atmospheres, thus causing the need for new styles and arrangements to be used.
hopefully you realize that I'm NO expert in music, so the whole analysis above is just my IMHO. 
What I want is more variety in her actual compositions
Oh, this we ALL would welcome anytime. What fan of what artist wouldn't?
Although it's just one of many things I'm friggin' WAITING for to happen... 
