Here's my perspective: I have a lot of woodwind libraries from many high-end companies. For the type of scoring I do, I often rely on the old Dan Dean Solo Woodwinds in Logic's Sampler to get my ideas across. Why? As a brasswind player with lots of performing experience, I need a few things that most of these more modern ww libraries running in Kontakt/Play/OPUS/Sine don't have - or have poorly-implimented:
1. Control over the "start" of the each sample (because so many samples have uneven attacks).
2. Fully editable, well-implimented ADSR (so I can shape the attack and release in certain situations).
3. Bone dry, consistent sound quality up and down every articulation across the entire library.
4. Super fast reliable load time - I'm not waiting long to get to the writing.
5. 2 Programmable low-dB-per-octave (very natural sounding) filters that can be mapped to ADSR or mod wheel (or any controller). So I can simulate how overtones respond to velocity of breath in all wind instruments.
6. Easily re-mappable zones across the keymap (if I don't like a particular sample, I can stretch a neighboring sample to fill the zone).
7. The ability to stretch the keymap lower and/or higher than the patch allows (great for situations where staying true to the natural range is not desired, either momentarily or across a whole track).
I guess it's more than a few!
The reason for most of this is that I care more about the "shaping" (tonally and dynamically) of the notes I'm programming to fit the musical passage than I care about having a million round-robins, mic positions etc.
The layperson listening to the music is not going to pick up on some of these details that most contemporary libraries are focusing on - but the details of a clean consistent attack, and ADSR shaping of each note (sometimes accomplished with cc's controlling relative volume/natural filtering) is impactful. For example I often use the ADSR to make staccato notes "more" staccato - in real world music making a staccato length can change quite dynamically given the tempo at play, nature of the music etc.
Just my two cents! I like control over the samples I'm using.
** I will say the one modern feature I really miss in the Dan Dean or any Sampler library is true legato.