(Apologies to get into this late, my 2 groats)
Any Warping from spont/formulaic spells aside, magical items take time and vis, and not every magi or covenant has that to spare, even if they wanted to.
More, sometimes this is saga-dependent - vis is rare in some sagas, and spending a half-rook or so just isn't attractive for those bonuses. Or this can be purely personal choice, on the part of the mage.
So, all things equal, Magical Lighting (& Heating) would be "standard" in the same sense that Air Conditioning is "standard" today in automobiles and homes - I've rarely had it over the decades, and rarely felt the need for it, but many do, and more have it anyway and are happier for it.
The "standard" is ample candlelight, which is what 99% of all magi would probably have grown up with for their pre-apprentice years and most (all but the most privileged apprentices*) for the majority of their apprenticeship, and thus is the "baseline", the "good enough" in the minds of most (at least to start with), even if far from optimal.
(* imo - and it's just one opinion - few Covenants would have magical lighting throughout the covenant, or even outside of a lab with such. Many Covenants would/could not, for fear of drawing unwanted questions from visitors. So except for such a private lab or the rare exceptional (Hermetic?) library, and except for the time an apprentice spends in that lab/library, it's the default - candles or daylight.)
Each StoryGuide, Saga and Player should make decisions like this for themselves, based on their understanding of several inter-connected factors, of simple "fun" as much as the gameworld and the rules, and their own preferred balance between those. I don't want to re-open this, only to offer an additional view at a "meta" level.
There are many, MANY examples of when the AM rules may be either unclear or uncomfortable (or at least debatably so) - Penetration, Wards, Might, Texts - how do they work in general, or in X specific circumstances, and "But what if..."?
And this is in large part intentional - many of the Authors did not want to over-define an effect that different playstyles may find over-/under-powered or appropriate.
And "permanent" spells using Ring/Circle fall into this potentially debatable, subjective category. (The very fact that it's debated proves it, by definition of the word, regardless of whether you, personally, believe the rules are "clear", one way or the other.)
So... what to do? Where to find "the answer"?
What I've always found most helpful is to go to the source - the true source, the original source. And that is the genre - all the books and movies and stories that inspire you to play AM, the ones that you like, not the ones you don't like! And think about how a magical effect within a "circle" or a "ring" works (and doesn't work) there - what they are expected to do, what their limits are, how they work in the story that you like so much (or how you would have rather seen them work!).
Because that's the same place the Authors got their inspiration.
And if you then still disagree - great! Then perhaps you aren't a huge fan of the same stories they are, and should play the game so you can tell the story the way you want to. Or perhaps you just don't want to hassle it - that's fine too, to handwave off any parts of the rules you find dull or constraining in favor of the parts you prefer!
But that's different, imo, from trying to twist the Rules As Written into something they might be (not that anyone is doing that here - but we've all seen it). Don't do that, don't sink to dull sophism - just smile and shout "House Rule!" and stand by it proudly. It's your story, it's your fun, not mine, not the Authors'.
There are 101 ways to Role Play, and every one is right - just not right for everyone. 
Good Gaming!
(And, yes, I have my own way of interpreting that particular topic, slightly different than any of the above, and would be happy to share it - but at this point, unless we're in a game together, it's at best moot and at worst askin' to stir up the whole mess all over again.) 8)