Yes: those netblocks belong to them and you can't take their stuff just because you like the look of it. There aren't enough addresses in v4. Reclaiming one or

Yes: those netblocks belong to them and you can't take their stuff just because you like the look of it. There aren't enough addresses in v4. Reclaiming one or two /8s here or there won't fix that. Before IANA runout in 2011, we were going through over one /8 per month, and demand has only gone up since then. Those class Bs you're so worried about would last the internet maybe 2 hours each. You can push as many allocations around as you like, but there just plain and simply isn't enough v4.