I don't bother with hiding it. But I do use an email with good spam filtering, a google voice number that sends all calls to voicemail and emails me any voicemails, and a PO Box I empty out once a month.
The reason I dont block it boils down to 3 reasons:
1. If someone wants to use WHOIS to make an offer I want them to.
2. Public WHOIS simplifies and streamlines proof of ownership for marketplaces like Afternic if a name is already listed by a previous owner who never removed it.
3. Not all registrars have free privacy and I am too cheap to pay for it. Though to be fair Epik has a privacy service that is free and can be used with any registrar, but my first two points still stand.
FWIW I find most spam actually comes in the form of calls but they never leave a vm. Looking at the logs for my number I get lots of calls, none seems to leave a vm though.