>It's not too difficult to "over-engineer" a solution. I've seen it over and over again. I'm in the camp of the "fewest moving parts wins".

Most of the newest web solutions are designed mostly to make an app scale and be faster over the wire. I'm betting that in 8 years you'll be able to run the biggest frickin' monolithic Windows95 EXE over the wire and hardware will be fast enough that it would be like running locally. Then all of the previous n-Tier/HTML/XML investments will be obsolete.