Upgrading D4.7 Site to D7 and Understanding Move Away From Taxonomy

TL;DR - What's the best way to get from 4.7 to 7? Upgrade through each version or try to import data into new install.

I've been out of touch with the drupal community for a few years, and I'm trying to understand a few things now that I'm coming back. I've been asked to upgrade a Drupal installation from 4.7 to the latest version 7.0. It was a photo publishing site that relied upon the Image module.

My main question about actually performing the upgrade: Should I attempt to upgrade the database by running the upgrade process for v5, v6, and then v7? Or would it be quicker to try and dump the data and import it into a new site?

The second question is more about what seems to be a "philosophy change". When reviewing my upgrade options for image.module, I came upon this passage in one of the guides:

Notice: This approach is based on the Content Construction Kit (CCK) and won't work with the contributes Image module. Image module offers a different gallery solution that is based on Taxonomy and views.

Why did the community move away from Categories/Taxonomy? It seemed like a powerful feature. I know that on certain occasions, some of the developers write posts on why some feature is good or bad, or their motivations for changes they make. Can someone point me towards a post like that? I'm having trouble finding something. I have a feeling it has something to do with CCK's integration into core, but I haven't followed the project closely since Drupal 5.

I know someone's going to ask why a production site ran such an old version for so long. Owner of the site was wary about making changes every time I attempted to upgrade, then we lost touch after a few life changes.