We have researched all aluminum construction. There are many disadvantages to this. Foremost ,the fact that this material is conductive, wich draws away the heat from where is should be - the vaprisation chamber. Price and manufacturability are other consideration regarding choice of using a polymer.
The capsule design, we beleive, has many advantages. For many users, it is less of a hassle to discard the capsule than to clean it. We expect the capsule price to eventually come down to a price where replacing it will be cost effective.
You'll find a lot of armchair pundits here who will jump at the chance to tell you how you should have designed your device or how you can immediately and easily improve it. This happens with every new vapourizer. Please excuse their ignorance in supposing that you didn't do your design research or just made poor design choices.