Its an intersting thread which has been discusse dquite a lot in these forums - but the OP makes some nice points namely the one very important point .

To a ordinary END USER ( don't think me and you and the geekly population of these forums please) - a nice looking and aesthetically pleasing application is more attractive and maked him / her download that rather than a very straighforward looking UI. Its just human nature, nothing else to it... (think about that analogy of the fit blonde woman and lets see who all raises their hands to decline a date with such a hot blonde attractive woman :-) )

So having said that one salient point - there is more to a good UI design than just good look - the look being an important function of the UI design.

It also needs to have a very functional and efficient UI - so that more can be accomplished with lessed clicks.

It need to be imntuitive - so a new user can easily understand the functional concepts of the app - that is why ICONS and animations help in the process - they are not always just for fluff.

It needs to be simple and designed for the device paragigm. This is my most important grouse about many of the Linux apps being developed (read ported) to the N900. You can't have a desktop application paragigm running on a handheld form factor. Its not good UI design - because it makes using the app damn difficult. While its good to have such a app in the case of nothing else existing (and I credit the developers who are porting these missing apps), it would be better to have the ported app being redesigned to fit the N900's usage paradigm - i.e. finger friendliness and mobility friendly.

A dedicated app for a dedicated function makes using the function easier on the N900. This goes to address the proponents of the "use a browser for all internet related functions" camp. While many of the apps we are used to using have been designed to run off the browser (a desktop browser) , often times it not efficine tUI wise to run the same on the smaller screen of the N900 browser - notwithstanding the fact that the N900 browser it damn good.
Its not the browser performance which hinders - its the screen size.
(for ex : on my train commute website - which lists my train timings, its damn difficult to hit the correct buttons with the finger - since its too data heavy. An application would have helped in this regard I am sure - by abstracting the data away from the layout elements that are in the
in the web page.
These are some of the major shortcomings when it comes to app design I believe. Dont get me wrog here - I am not criticizing all the app developers - I am just thinking aloud as an end-user - if thats adds any value to understanding what an end-user wants (me being a small fractional representative).