I don't bother to complain about those Acolyte tracks but mainly because I simply dislike them. Ironically for someone saying "Well why shouldn't he have vocal tracks!" the only VOTA track I actually like is Tower
Funny how we are all so different, isn't it? I tend to view Acolyte as his best album (you know, that old 'best album Genesis never made' saw)... and the track I like least is... Tower! (Too cinematic by half, like much of his later output... Still, it works very well as part of the whole thing).
I wasn't aware the guest singers issue was a common complaint regarding Touch. But again, in a sense a moot point as it's an album I struggle with. I'm not sure I even like anything at all on it.
I haven't listened to it in years (while I always come back to VOTA), but for me it stands on the merits of its collaborations – Narnia, How Can I, Hoping Love Will Last, Icarus Ascending...
You're right in what you say about his voice in that it's not bad but definitely not that good. It's a bit characterless. But it's obviously bad enough to make you wish he'd either hire guest singers or just do instrumentals!
Not just characterless - paper thin, with a very slight but unpleasant rasp to it. And since he's trying so hard to get something half decent out of it, it comes out flat, uninflected, devoid of any personality/phrasing. OK, characterless... and totaly unnecessary.
In-fu-ria-ting 
I think he's long produced his definitive album, which in my view would be Spectral Mornings. I don't think there's anything left in the tank to enable anything on that level, guest or no vocal.
Judging from the smattering of fairly recent tunes of his I've listened to on YT these last few days, I'd say he's lost in a furrow he shouldn't have tried to plough in the first place – but that he could still surprise us if he let his instrumental/classical leanings take over once and for all. The instrumental parts are always outstanding, it's just that there is a general lack of direction (Under the Eye of the Sun is very good in its Yes disguise, hafta say 
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Again, I'm sorry he probably won't come up with an electric follower to Midsummer Night's Dream... Something written to the hilt, unhindered by lyrics writing & singing (which, again, must take up an enormous amount of time and energy), or by any commercial considerations... which in Steve's case are a moot point anyway.
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