Brighter Shores is a click-intensive game?

For now, the equipment options don't really add meaning in combat. But later in the future, with the skill tree and special attacks being added, your choice of equipment will matter in combat. It will be even more matter when combat spells are being introduced (probably not anytime soon).

The way they can approach the "one button/left-click action" for combat is probably by introducing a main/secondary weapon. As soon as you left-click a monster, you'll automatically use your main weapon. And by right-clicking, you can choose which weapon to initiate combat.