Need and want are certainly the issue. That said, even a VFR pilot with a clear view of the ground and chasing his finger along a paper chart can benefit from panel mounted display showing current winds aloft, TAS, range, ETE, traffic within 20 miles, and weather within 100, etc. Yes, one can fly just fine without even looking at the panel, but this stuff is right there, free for the taking. Even buying a basic six pack is going to cost more than an EFIS - with far less utility, more weight, and more complexity. The days of steam are coming to an end.