There is some great advice given here.
You said your wife is reserved and despite you both talking about her being more adventurous. She is probably happy with the sex you are having already (you said it is good).
It doesn't mean your wife is reserved but probably has no wish to be more adventurous. While it's good to communicate, you have to go about it in the right way. If Mr KB said to me that he wanted me to be more adventurous, I would feel blamed and useless and that his sexual happiness is all down to me and my actions.
In answer to can people change - yes they can and they do but they have to want to change for themselves not from pressure from their partner.
Myself and Mr KB were very vanilla until a few years ago, it was boring, mundane and ended up virtually sexless. It came to crunch point so we talked and put a plan in action. We bought toys, discussed fantasies and learnt along the way together. Neither blamed the other it was 50/50 and now it is great and when we have a blip we talk, but it is mainly about life getting in the way.
If you aren't satisfied, you have to work together, be her guide if she is clueless on what you want as she isn't a mind reader. Let her know when she gets it right as she will be more inclined to do it again. Everyone wants to please their partner, your wife included. She just doesn't know how or what you want.
I didn't know what I liked and a lot don't until they experience a certain thing, that does it for them and your wife could be the same. This forum can make it look like all the women on here are adventurous and hot and a lot are, but you have to remember this place is just a small cross section of the general public and not everyone in the real world are the same.
When the time is right you could point her to Lovehoney just to see if there is anything she wouldn't mind trying but take it slowly without pressure.
You already have a good sexlife which is more than a lot of us had when we started coming here, so you have an excellent foundation to build on together.