Forty years ago this August, I steelhead-fished the Deschutes for the first time. Has it changed since then? Hellya! Is it worth it to go again? Hellya for me, but who knows for you. There are, indeed, more people. There are likely the same proportion of great, so-so, and "other" people on the river. Just more of them.
I suspect that there is a world class footrace up from the mouth every morning when the fish are in. If you're somewhat ambivalent as to which rock you start flinging from, you can probably walk up any time of the day and still stand a chance of touching a fish when they're in.
If you're after a pristine experience, hire a guide to take you up (or down) the river to escape the walk-ins and congested areas. Or, go fish it in early to mid-July. Or, fish it in October. Or, fish a different river. It won't be the same, but it can be great.
Remember though, you can't go home.