Both mindsets are necessary, and it's also possible to go too far in both directions. I've been on teams that took planning to an absurd end, which resulted in obsolete plans as soon as implementation started. I've also been on teams which went around in circles because they didn't have any direction and their implementation/discovery wasn't focused on a clear goal.

Long term plans are only inaccurate or wrong if they're over reaching. Plans, like every other part of a project, have to be able to change and grow throughout implementation. It's not long-term planning that is the issue, it's the stagnation of overbearing plans.