To answer your question, no, I don't think adding that many lines in htaccess etc. is a good solution. As you suspected you only block already detected bots.
Its more efficient to use a list like spamcop https://www.spamcop.net/fom-serve/cache/291.html and Apache Spamassasin https://spamassassin.apache.org/ directly on mailserver level to protect you from incoming spam.
In the end the brain is your best protection, in combination with the tools available. Unfortunately you need to spend resources to stay safe long-term.
1. Limit the amount of emails displayed on site(s).
If possible change to a submit form where visitor enters his or hers email and you contact them rather then showing an email in clear-text. If not possible, then make sure to have only 1 email displayed on the website, and then monitor that inbox like a real webmaster should. Anytime you receive spam or infected emails make sure to add the specific unique thing in that email to a spam filter so that any future email with same characteristics gets completely ignored in the future. This takes some practice but works great. You will be amazed how predictable most spam is. In time you get less and less "bad" emails. Be careful not to block legitimate emails creating too sensible filters though.
2. Educate the email users.
You can never stop "bad bots" completely (they are not bad at all, they are great, but the people that use them are bad) and you can spend endless resources trying to do it. It is on the other hand easier to educate the users of the emails connected to your servers. Make sure they understand to never open an attachment or click a file or even download one unless they have previously confirmed that they know the sender and are expecting such file, and even then be suspicious. If an email is unexpected, don't open it, but if possible forward it to you as webmaster etc. Educating people about how to use email safely is easier then stopping hackers from sending infected emails.
3. Don't worry, but be serious about security.
Don't go around paranoid worrying about bad bots and such. It's nothing to worry about unless you have something to steal. If you do have something valuable, then learn how to protect it. Make backups. Store backups on external servers in other data centers. Be serious about using latest version of scripts and keep an eye on security patches etc etc. Stay up to date!