This is a good start to an article, but it's more of an advertisement than a convincing argument. Why? It's all upside.

You don't acknowledge the costs of clustering: hardware, licensing, implementation and administration time.

A full rational argument sets out the costs and the benefits and shows (in a positive case) that the benefits outweigh the costs.

I would love to see a part two to this article which fully covers the costs of clustering, as enthusiastically as this one covered the benefits.