Some are interested in using a HRM, some are not. It's not a universal answer.
Many already use them and some people will start to use them since it happens to be included.
It's not just a curiosity seeing your HR. It's valuable data for some and fitness strategies are worked out using it.
For instance, if your waking HR is 65 every day, then one morning you see it at 83, you can learn from that.
If you've been working out a lot, it would mean you need a rest day or go easy day so you can recover and not over train.
Some need to work out with a specific intensity. Some HR ranges are ideal for burning fat and you may use the HRM to keep track of it so you can pace yourself. If you are slowing or going too fast it will prompt you to speed up or slow down.
Some people need to do intervals... A portion of the effort is within one zone, then followed by a higher intensity effort above a certain rate, then back into the easier zone, rinse and repeat. It's a powerful strategy.
If you're not familiar with these concepts, and you're interested, poke around online and learn about how to use a HRM effectively, it can greatly benefit you.It's most used by runners and cyclists, but it can be useful even for walking. When you see how low your HR is while walking, you can choose to walk fast enough to get it above a certain rate. You tell the monitor to keep you above, say 100bpm, and it will warn you if you fall below that. It's a great motivator. Honest.
EDIT+++ BTW, one of the reviewers, a woman, said the HRM of the Watch was very close to the reading she got from her heart strap. So that is very good news.