The difference is that fusing will come off eventually creating bubbles on the front of the jacket. Washing or dry cleaning would speed up this process a lot. Can't complain about that in a jacket for 200-300$ but not in a 3.5k$ suitAs mentioned, worse than ideal is not BAD. Unless you're using your tailoring trekking through insanely humid jungles, you're unlikely to notice dramatic differences (marginal ones, no doubt) in the wear/tear and long term viability of the garment.
As with most things, truth lies in the grey area between extremes.