That's rather the point. There is no way of saying if a subscription skillwire service is viable at any given table. I don't think it's good to suggest it as an option to make skillwires more viable, since we have no actual frame of reference for it.
Skill 4, or 4 +1, is still not that impressive, since skill is only part of the equation these days. In SR1-3, it was almost *all* of the equation, so it mattered more. But in SR4.5, the costs of buying skillsofts was prohibitive, and the costs of subscription are a mystery. SR5 doesn't have a subscription service at this time, so we can only go by the book costs, which are insane. 30,000 for a level 6 skill? That's a huge chunk of money, especially if you're trying to get a lot of skills.
As for your last point: Back in early SR3, a friend and I designed two characters to work together, a skillwire samurai and a drone rigger/data specialist. Storage memory was still a thing in those days, so what we did was have me carry all this skillsofts. The silly drone rules said that all drones has three full-band simsense channels running, each; so I just had the drone plug into the skillwisres, and remote-downloaded any skill he might need. By the way: his name was Dozer, and my rigger was Tank.
Skillwires are good for two things: Having the right skill on hand, and becoming an instant expert at everyting. Unfortunately, skillsofts cost so much, it's impossible to stock every one you might need. Also, skillwires are for when you need an instant expert. Unfortunately, a rating 4 system just isn't good enough for that.
Indeed... Skillsofts became crazy expensive in SR4A (Sr4 Prices were good, in my opinion), and they did not solve anything in SR5 because they jacked the hardware up to astronomical (Insane and Ludicrous also come to mind as descriptive words for this) prices and the 'Softs are STILL too expensive.
