This is because better resolution is not always better. There is always a tradeoff between resolution and signal to noise. Besides, not all samples even have high Q peaks. Different experiments demand different measurements. One final comment.
People tend to sweep imperfections under the rug.
For very short wavelength machines, the asymmetry can be severe for the bulk of the pattern. Same is true for other types of aberrations. High resolution at low Q is handy for indexing, and is essential for tackling moderately complex magnetic structures with powder neutron data. Peak broadening effects and splittings can be easier to interpret where there is less peak overlap, so high resolution in this range can again be useful. It's a question of applying the right instrument or setup to the particular problem in mind.