I think your review and photos will be helpful to many. You make a very good point which others may have missed--the LSR30X were never designed to be computer speakers although they can sort-of work--if you have the space.
These are professional powered studio monitors that were designed as a tool to be used by audio engineers and music producers. Their price point (especially now) makes them appealing to home audio enthusiasts; however, comparisons with consumer audio equipment will definitely be an apples to oranges affair. For a fair comparison of features, performance, and sound quality, check out the Mackie MR5mk3 ($240/pair), M-Audio BX5 D3 ($298/pair), or Yamaha HS5 ($400/pair).
The tonal balance of the LSR30X is intended to be useful to professionals for identifying and correcting issues with the mix rather than to be pleasurable to listen to for entertainment. There is enough bass to tell what's going on without masking or obscuring details. More bass output might be more enjoyable, but it it is not necessary and would make the LSR30X less effective as a tool.
Although the cabinets are fairly large for a 5" 2-way, the laws of physics limit the depth and level of bass that is possible at acceptably low distortion. As car geeks say, "there's no replacement for displacement!" Also, as you have pointed out, for deeper bass, a powered sub (or two) is the way to go. Although not the equivalent of a sub, the original version of the JBL LSR308 (with 8" woofers) is now available, until they sell out, for $300/pair, which is a crazy good deal for those who want more bass, have the space and don't care to spend for sub(s).
The JBL 3-Series LSR monitors work well in nearfield applications but really benefit from installation on proper stands vs. setting them on a desk or table. If you are impressed by their soundstage now, just wait until you have them on stands! As I've mentioned elsewhere, lows benefit from a little room gain, so try placing the stands 1 - 2 ft from the rear or side walls if possible.
At their price point, the JBL 3-Series has always been tough to beat for their intended application. They can work acceptably well in consumer audio applications with due care given to placement and connections and perhaps with judicious use of equalization to achieve a more pleasing tone. Cheers and happy listening!