But the reality is that both the career advancement and funding for further experiments is almost entirely based on the number of publications in prestigious journals.
And effort put into collecting data is not by itself publishable: you must add analysis, and very often analysis that successfully confirms a new hypothesis or invalidates previous beliefs to publish. Journals prefer to publish exciting results, and "we ran experiment X, and found no significant effects" is usually rejected.
Fixing this is desperately needed, but so far nobody has come up with a solution that would actually fix this.
A middle ground would be to require data publication after a certain time period. For example, NASA and ESA release original data 6-12 months after collection. Releasing original data together with the paper also works.