what will the museum of the future be like?
You made some very interesting points that are really making me go "hmm..." My thesis work focused on how there is a disparity between museums disseminating knowledge primarily through transference and how people access and acquire knowledge outside the museum- primarily by sharing and re-sharing it. I further argue that in order to change this disparity, museums should change their philosophical perspective of their view and value of the visitor, primarily by allowing the visitor to be part of extending the interpretation of artifacts, exactly as you say the "manipulation of information." But you have an interesting point, can the value of artifacts lessen if museums become primarily touch screens? While I argue that if a visitor can gather more meaning and understanding by looking at an i-Pad than the object, what is the harm? But, instead of having the "either or" argument of a touch-screen-based museum experience, how can the two actually work together, such as the touch-screen provides tid-bits of information where you need to look closer at the actual object to get that "wow" factor. Hmmm.....
If you watch visitors in museums that are using screen based interpretation especially multi touch screens you will find that they are busy playing and having fun, not necessarily a bad thing. The question is are they actually learning something or absorbing what they are seeing. I've also noticed that less time is spent looking at the artefacts on display and more time looking at the screens, afterall their bright, colourful and often have motion graphics just like tv. But this does not necessarily lead to a enhanced learning experience which is how they are often justified in design meetings.
I have yet to see comparison research of learning outcomes from traditional printed interpretation panels as opposed to multi media screens. I think that it is critical that researchers help us with proper studies on what learning actually happens when using these technologies so that museum staff and designers have benchmarks to work against when deciding how much of the budget goes to technology.
As you mention touch-screen content needs to prompt the visitor to explore the actual object and in this case I see some value in installing them. But to often they are used for static text, photos or 3d renderings that don't provide any more info than looking at the actual artefact. As designers we need to emphasize that if we don't have enough money in the budgets for solid well thought out content development we are actually doing the visitor a disservice by installing screen based interpretation because it will only distract the visitor from what they originally came to see.
This will be an uphill battle because touch-screens are seductive and they enliven what can be a rather dull exhibit. But let's all remember it's not the screens that add value to the visitor experience it's authentic content.