Why have we never been able to modify audio channels once a clip is added to a sequence? I'm guessing there's a good reason Adobe has never had this feature. The lack of this feature is explicitly mentioned a few times in the audio section of the Premiere Pro CC manual, as if it's a benefit NOT to have it. But the benefit is entirely lost on me.
In my workflow, I synchronize my double-system video and audio before anything else. I do this in PluralEyes (and unfortunately I'll have to keep doing it this way, until PPr's sync on sound feature gets fixed—for me it's never worked).
Once PluralEyes has synched hours of footage and audio and placed it on a PLURALEYES GENERATED sequence, I import that sequence into Premiere. Note: Since I haven't gone through the step of creating a blank New Sequence, I don't get the opportunity to setup my audio channels the way I'd like in my sequence (i.e. Stereo recordings should occupy ONE track, not two. Typically these tracks come from a camcorder and are used for reference sound, or ambient noise at best, so I don't need them taking up precious real estate in my sequence).
Since PluralEyes doesn't merge my clips for me (or rather I don't want it to since I'm usually doing multi-cam sequences where I want to keep all 14, or so, tracks of audio), I have to go through the clips one by one and do a Merge Clip action once I've adjusted any minor sync issues, or determined which tracks I actually want to keep. But, and here's the key, at this stage I'm not yet 100% certain whether I'll use the nat sound or the wireless mic sound (separate audio recorder, etc). Furthermore, I don't really want to think about that at this point. After I've spent a few mind-numbing hours just ingesting files, sync and merges, I want to jump into the edit as soon as possible, before I lose all will to finish this edit. If I modify my audio channels right now, I'll lose the ability to make some creative decisions later on.
I'd like to start whacking out an assembly edit. And then after I have a rough program, I can start looking at which audio tracks (nat or double-system) I like better in each circumstance. This is where I become stumped that at this stage, I'm locked into whatever audio channels I've setup (or not) in the earliest stage of the edit, back before any media was actually on the timeline! It's at this stage, and usually only at this stage that I want to start Modifying Channels—FROM THE TIMELINE!
Does anyone else feel the same? If not, what is your workflow?
Feature Summary: Right-click on any clip, (master clip, sub-clip, merged, nested or otherwise) in the timeline and choose Modify > Audio Channels.
I've submitted a feature request, with a link back to this discussion, so please pipe in—especially if you want this feature. 
