Don't just dismiss PageRank. Remember, it is still at the core of Google's algorithm.
Although
PR doesn't often reflect the ranking of a website in the SERPS it does have a profound effect on the indexing of a website.
Therefore, a small site with low
PR will do fine if well optimised with a few inbound links. But a big site with thousands of pages needs a high
PR to get all the pages indexed well and frequently.
Indexing is a major factor in the success of a website.