This is the answer! Information density is not inherently a virtue. For many tasks, you want to focus the user's attention, which usually means less density. But professionals often want as much as possible accessible from a single screen, so they don't need to click around too much.

In addition to creative software, look at professional stock/crypto trading platforms, EHRs, POS systems, CRMs, or any software targeted at a vertical—veterinarians, fleet management software, etc. Many of them will run counter to "good UI" best practices. But if you interview their users, you might be surprised by what they love about these interfaces.