I used to think that complex objects were important and that packaging standards were going to be critical for the future of managing learning and/or research objects. For example, the JISC Information Environment Technical Standards document (wot I wrote) says:
Resources that comprise a collection of items that are packaged together for management or exchange purposes should be packaged using the IMS Content Packaging Specification if they are 'learning objects' (i.e. resources are primarily intended for use in a learning and teaching context and that have a specific pedagogic aim) or the Metadata Encoding & Transmission Standard (METS).
Now I'm not so sure. Les Carr, over on RepositoryMan, seems to have reached the same conclusion.
For some time now I've argued that the Web is made up of complex objects anyway (in the sense that almost every Web page you look at is a bundle of text, images and other stuff) but that the Web does well to treat these as loosely-coupled bundles of individual items - items that are to a large extent managed and delivered separately. In some respects (X)HTML acts like a simple packaging format, using the <img>, <object> and other tags to link together the appropriate bundle of items for a given Web page but leaving the client to decide which bits of the bundle to download and use - a text-only browser will behave differently from a graphical browser for example.
Our attempts at more explicit tightly-coupled complex object standards, in the form of IMS CP and METS for example, have resulted in objects that are useful only in some of the systems, some of the time (between a learning object repository and a learning management system for example) but that are largely unhelpful for people armed only with a bog-standard Web browser.
What do I mean by tightly-coupled? It's difficult to say precisely! It may be the wrong term. One can certainly argue that a METS package in which all the content is linked by reference (as opposed to being carried as part of the package) is not hugely dissimilar to the situation with (X)HTML described above. But there is one massive difference. (X)HTML is part of the mainstream Web, other packaging standards are not - when was the last time you found a Web browser that knew what to so with an IMS CP or METS package for example? So maybe the issue has more to do with the solution being mainstream or not, rather than about how tightly-coupled stuff is?
My concern is that repository efforts that first and foremost treat the world as being made up of complex objects that need to be explicitly packaged together using standards like IMS CP or METS in order to be useful may take repositories further away from the mainstream Web than they are currently - which is not a good thing. IMHO.