I run a small business outside of my residence, including simple PC repair/web design/and also occasionally act as an apprentice for setting up soho networks. The rules per our ISP explicitly say 1 network per residence. I mention I run 12 pc's in total (many are old dual linux OS's that I use for workstation studies which stay in their own little world for the most part, yes). It is absolutely integral that I provide any customers a safe workplace. THe biggest issue is my roomates constantly having network breaches. Im not sure how familair you are with pentesting. But pivoting around a network once inside is not rocket science if you have a little bit of pentesting experience. So sharing a network and running a side business (I have my A+,ceh v9, and currently studying for my comptia security +) IS a pretty serious task considering the attackers that have gotten through in the past. and let me tell you, they were not very skillful, mostly copy/paste script kiddies and botnets who leave all of their footprints behind. But I may not always get so lucky, thus the idea of running something with IDS is a fairly serious one, atleast to me. I will tell you that I have dealt with over 4 breaches over the last 2 years. all most likely from SE phish emails, or porn drive-bys.
Learning is of course a part of everything. But this is far from a toy, it is more stress and frustration. However, i do agree with your premise in most general cases.
EDIT:
IPS/IPS are mostly used when you have a actual server exposed to internet. Almost nobody runs a web server from their house. Even small business have moved this to hosting sites.
apparently you haven't been keeping up with the current exploit-db. one very effective exploit at the moment is running malicious websites from a server windows network in something like a super generic 'about me' page RCEs and other in varioous web code exploits are running right through not only windows defender, but kaspersky, malware etc! I kid you not, this is a very recent discovery ;P