"Only once you have turned over your cluster to single purpose, Java-based HDFS monoculture. And if all your processing needs can be force fitted into that monoculture's way of working."
That is simply not true. Look into Hadoop streaming.
"My needs, resources and pockets do not lend themselves to such."
That's too bad. I am currently working for a company and we are in the process of replacing our traditional means of processing the extremely massive volumes of data we consume with Hadoop. It is beyond awesome. Again, you should check it out instead of making assumptions. Cheers! :)