I see it more as only 13 current packs, since I don't see SP as taxing on a system. It's just stuff. So, by the end of the year, we'll have 15 packs that really matter. But I am not surprised that some people have issues with all packs installed on low end pc's.
I was actually just talking to my husband about this same subject a couple days ago. I'm sure, at some point, it'll start being too taxing on even more powerful pc's, but hopefully that day isn't coming anytime soon. I imagine when that day does start to come, they will decide to move on to Sims 5.
I do think the devs don't intend for people to buy every pack, even though a good majority of people do.
