Why are bots from Microsoft visiting my website and eating bandwidth?

Question

I'm not talking about bingbot or msnbot (although their tens of thousands of visits are worthy another discussion), no, I'm talking about these:

deny from 20.120.134.35 20.26.44.160 20.197.112.233 20.27.20.24 20.99.210.78 20.120.134.34 20.27.20.28 20.27.20.19 20.27.20.18
deny from 20.197.112.235 20.99.210.65 20.120.134.38 20.240.13.241 20.83.25.251 20.223.140.8 20.117.224.21 20.120.134.37 20.99.210.73
deny from 20.99.210.77 20.99.210.74 20.120.134.41 20.240.13.254 20.120.134.33 20.27.20.21 20.26.44.162 20.197.112.237 20.26.44.173
deny from 20.240.18.33 20.240.18.34 20.210.58.96 20.210.58.99 20.99.210.67 20.120.134.32 20.26.44.166 20.26.44.161 20.240.13.253
deny from 20.27.20.23 20.197.112.227 20.26.44.174 20.99.210.75 20.26.80.128 20.120.134.36 20.26.44.167 20.26.44.164 20.120.134.44
deny from 20.27.20.27 20.27.20.16 20.197.112.224 20.27.20.26 20.26.44.172 20.26.80.131 20.120.134.43 20.27.20.29 20.240.13.248 20.240.13.243
deny from 20.198.193.96 20.240.18.32 20.240.18.35 20.120.134.40

...and counting (every day a few more). Why? What are they doing? There is no note of a 'bot', 'crawler' or 'spider' in the User Agent (UA). Why are they pretending to be human? They also CONSTANTLY visit long gone pages. No matter what I serve them, a 301, 404, 410, they keep getting back. I don't have a big website, I do have lots of images. They keep eating resources and connecting to my database. So my question is: WHY are they visiting and pretending to be human? What's the reason? Plus, can someone give me ALL microsoft bot (except MSN and BING) IP ranges so I can block them all? Thank you. (PS I had to add tags, so I chose random ones). I don't run BING ads nor Google ads, nothing.