Low-sensitivity speakers — What's special about them?

I'm building a system for a smaller room (need smaller bookshelves), and I did a bunch of research and some listening. I am attracted both to the Dynaudio Evoke 10's (heard locally) and the Salk Wow1 speakers (ordered and I'm waiting on them for a trial). I have a Rel 328 sub.

Here's the thing — both of those speakers are 84db sensitivity. Several people on this forum and my local dealer have remarked, "You should get a speaker that's easier to drive so you have a wider choice of power and can spend less, too."

That advice — get a more efficient speaker — makes sense to me, but before I just twist with every opinion I come across (I'm a newbie, so I'm pathetically suggestible), I'd like to hear the other side. Viz.,

QUESTION: What is the value in low sensitivity speakers? What do they do for your system or listening experience which make them worth the cost and effort to drive them? Has anyone run the gamut from high to low and wound up with low for a reason?

Your answers to this can help me decide if I should divorce my earlier predilections to low-sensitivity speakers (in other words, throw the Salks and Dyns overboard) and move to a more reasonable partner for a larger variety of amps. Thanks.
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@mrdecibel as always I so enjoy our measured and reasonable exchanges based on mutual respect for different tastes :-)
More and better bass out of a smaller package with the right beefy amp capable of delivering it. 
I think it’s a common misperception that smaller speakers mean you can have a lesser amp to drive them. The exact opposite is case if the speakers are good quality and you want to get the most out of them. 
I listen to music using Magnepan 20.1s, which are a 4 ohm and 85 db sensitivity speaker. Yes, they require some power to drive, especially if you don't want your amp to overheat. But you don't have to pay a fortune for an amp that can drive them. Emotiva has the A-300 amp for $400 right now and it has 150 wpc at 8 ohms and 300 wpc at 4 ohms. The 300 wpc is enough to make the Maggies sing.
What it comes down to is... really good mids with any type of top end extension without cone break up is hard to find in true high sensitivity speakers.
The Classic Audio Loudspeakers use a beryllium diaphragm with Kapton surround in their compression drivers; the first breakup is at 35KHz. The model T3 which I have at home is 97dB and 16 ohms, flat to 20Hz owing to dual TAD 15" woofers.