The pursuit of a meaningful life puts way too much pressure on identifying what is meaningful and worth our energies. That would probably decrease my happiness.
What if I can't find any pursuit that I consider to be the most meaningful? Am I OK committing to something that could potentially be less than optimal in terms of meaningfulness?
It isn't that important for me to evaluate my actions on meaningfulness - I'm bound to disappoint my self by that metric.
Prioritizing meaningfulness over happiness is putting the cart before the horse, in my mind.
Upon deeper introspection, my own personal experience of “happiness without meaning” is closer to “the meaning is just the universe/physics unfolding (and I happen to be a part of that)”, which is so all-encompassing that it has little meaning itself, in the Kolmogorov complexity sense. And concomitant well-being, which I would define as closer to “completely neutral affective experience” rather than the “positive affective experience” described as hedonic well-being in the study you referenced.
Of course, I understand that achieving happiness can be challenging, and that seeking meaning can be a meaningful step on that path.
But it is possible to have happiness without meaning, and that seems more valuable than meaning without happiness, or happiness that relies on a sense of meaning.