1 free magic point with the quality. Boosting most skills are .25 to .5 points. An easy 2-3 extra dice to share among a couple of skills for 5 bp. Most builds stay above 1 essence so that isn't much of an issue.
Really I can see why people call it Magicrun at times. "You good at your job? Well as long as you stay above 1 essence you can always make yourself better for a minimal investment."
If I misunderstood how Essence and Magic interacted with one another, I might call it MagicRun, too.
Essence does not merely set the cap for your potential Magic score. Essence lost (at character creation or afterwards) lowers your Magic. Period. If you spend 5 BP for the Adept Positive Quality, you receive 1 Magic Point. If you do not spend the BP to increase that Magic above 1, the purchase of
anything that negatively impacts Essence -- a datajack, let's say -- lowers your Essence to 5.99, and your Magic to 0.
Congratulations, you've built a burn-out.
In order to mix augmentation and Adept powers, you need to buy your Magic up (capping, and costing extra, at 6 during character creation), and then knock it back down for every bit of Essence loss you pick up mingling in 'ware. You're throwing BP out the window, in other words, in order to try and purchase
and maintain an effective Magic rating, if you dip too heavily into augmentation.
You can't make a hardcore Street Sammy with just 1.01 Essence left, and have
any Adept power points, in other words...unless you bought his Magic up to 6 (including the extra cost for capping it), at which point you'd have 1 Magic point left (and would be capped at 1 level of any power, as per the usual limitations) to be a "better" Street Samurai.
Hopefully this clarifies the rules situation for you, and will let you re-evaluate your "MagicRun" condemnation, at least where Adepts are concerned.
I tried and failed, repeatedly, to make an adept who didn't have Sensitive System, wasn't a sapient critter or other "no ware lolz" species, and would from a pure optimization standpoint not want 'ware.
Which is a flaw with the core SR4 rules, and one I've bemoaned for years now. I think the primary culprit is the criminally overpriced attribute increases that Adepts get, compared to the efficiency of similar augmentation through mundane means. If you can get basic Muscle Toner for .4 to increase Agility from 6 to 7, and it costs 1.5 to get the same increase through Adept powers...yeah, it's a no brainer.
I partially tried to help with just those same sort of characters in
Way of the Adept by offering power discounts, but it was beyond my reach to just outright alter the prices of Adept powers, unfortunately. It's something I hope I'm still around to bitch about when SR5 is getting worked on.