are hiking boots necessary?

It depends on what you mean by "hiking boots" and what you mean by "travel to Interlaken and the region."

If by hiking boots you mean a leather boot with a rigid sole with steel shank--then no, this is not necessary or desirable, unless you're definitely planning to hike in the mountains at elevations where there will be snow or slush and you'll be wearing crampons, or engaging in some other kind of specialized/technical alpine experience.

If by hiking boots you mean something lighter and more packable, then the answer could be different.

We could be more helpful if can be more specific about your activities and location.

If you only plan to walk between the villages, or on some of the well-tended gravel trails, no, you don't need hiking boots, regular walking shoes will be fine (as long as it doesn't rain, which is always a possibility). Hiking boots would be more of a necessity if you planned to hike at the higher elevations, where the trails are more uneven.

For anything up to and including well traveled trails, a good walking shoe (or even sturdy sandal) will work fine.

If you're planning real mountain hiking, however, you will want some traction. I recommend either light hikers or trail running shoes. They are about as light as a pair of running shoes but offer more traction and more lateral support than regular running shoes. There are lots of brands to choose from, so you're certain to find something that fits any type of foot.

Happy feet = Happy Trip. If you have a lot of cobblestones or castles or hiking trails... then haveing good sturdy shoes is key. There are plenty of comfortable low-hikers available. Ecco has good solid shoes for all - and Merrel is great for various Hiking boots/Shoes. Both brands have goretex which can be handy if its wet. They even come in darker colors so you can wear them to nice restaurants or events.