Laptops and increasing mobility

Why is it that Computer makers suddenly feel the need to make everything smaller?  Reducing the size of components is a good way to afford higher capacity and/or speed by having more components in the same amount of space, but when I see a subnotebook or UMPC as they’re abbreviated (ultra mobile personal computer) with a screen size under 10″ I die a little inside.  Why?  Flooding the market with hundreds of UMPCs sporting the processing power of a Pentium II or at best, III, cannot be good for improvement of general computer systems.  What I’m saying is that making things smaller and less fast and/or with lower storage then current generation (or even in this case a few generations) is not productive toward advancing the technology of computers.   It’s all about marketing it to the “mobile” youth who are extremely computer literate and demand entertainment whenever  they’re bored.  Even the macbook air makes me sick.  The plain old macbook outperforms it, and costs $700 less.  It’s .75″ thin and they tell you that that’s a good thing.  my current laptop is about 2.1″ thin and it’s already too thin and fragile.  Probably the worst aspect of the new UMPCs is that the boot up times and lag with everday tasks is terrible.  Most likely due to the fact that they run Vista and Leopard on  what could be desribed as outdated hardware.