It is important to do so regularly to support witnesses, which are actively contributing to the HIVE ecosystem.
HIVE witnesses basically verify blocks before they are added to the blockchain and thus help to ensure their validity and correctness. Besides that witnesses may contribute in the decision making process and the future of HIVE.
Every account can vote for up to 30 witnesses, which results in a ranking of witnesses according to their total voting weight. The top 20 witnesses, plus one witness from the remaining ones, are then verifying new blocks.
There are numerous tools for voting, including my own, which you can find at https://primersion.com/witnesses. Just enter your HIVE username and you will immediately see on top (in red) if any of your witness votes is outdated.
Other tools:
https://wallet.hive.blog/~witnesses
https://peakd.com/me/witnesses
https://ecency.com/witnesses
...only to mention a few.
If you like what I am doing, please support me by voting for my HIVE / Hive-Engine witness using my tool or directly:
HIVE (using Hivesigner)
Hive-Engine (using Votify)
