I agree entirely. What is worse is some of these themes are just begging for clarification (Alchemist, Order Adept, Wizard Apprentice), poorly thought out (Beastmaster) and one is just much better than the others (Order Adept gives a +2 bonus to will at level 5, which is a pretty substantial increase compared to the others). While I honestly can put DS themes on tiers, there isn't anything outright bad or that penalizes you for taking it.
I also wonder about confusing rules elements, like taking the Apprentice Wizard theme, then getting your free item and retraining it out after level 6. What happens to the free item? I mean such stupidity in an ongoing campaign is easy to stop, but it could lead to hilarious encounters/LFR hijinks.
Honestly, I don't know anymore and it's become clear that stuff pre-essentials is no longer important to wizards.
Edit: I actually agree with you Obryn. While their power level varies hugely within themselves, it's the fact they grant extra features over powers (that need your normal slot) that changes them considerably. Additionally, Order Adept can let a wide variety of classes get some of the best defensive utilities in the game (as they can take wizard utilities). I wouldn't think anyone would take some of these over a Dark Sun theme, but the Order Adept is incredible and I can see anyone wanting that. Getting wizard utilities like shield and wizards escape is just invaluable for so many classes (plus the +2 will defense). I'm just really underwhelmed at the current design in 4E and really unhappy they removed the power swap feature - instead replacing it with features. Yes, I know that works well with essentials classes - but I am not concerned about that at all. I wanted something that works with the vast majority of everything currently in 4E: Especially as themes would be substantial and REAL support for pre-E classes. Well, what a shame there.
It was very hard to say that Dark Sun themes were power creep, even if they added a free encounter for nothing because all the normal restrictions on powers were there beyond that. A theme that grants 3 extra benefits (with an encounter power) is considerably more powerful in many ways. Then again it depends on what those benefits actually are.