I "kind of agree" and "kind of disagree".
However, my strong believe is that PIN diodes for T/R need to be looked from all perspectives, not only from perspective "because it is innovative". And, additionally, the feedback (which is coming with PIN diodes embedded), has to be understood.
Definitely, why everyone is still using relays? Obviously, because of two reasons: 1. It is much cheaper and 2. It has dedicated channels for signal and RF circuits.
As for 1: while pushing EE towards PIN diodes, make sure you understand that the price of DX-PIN will immedeately bump up 300+ bucks. And EE transceivers are very good in price (personally I really prefer it stays this way).
As for 2: we all know that good designed Mux-Demux is costly. In time/money it means a) programmers will spend valuable time to design and embed PIN diodes, and b) it means another bump up in price (due to conversion from time to money) - and this bump, believe me, would be twice as price for physical PIN diodes.
Do not interpret me wrong - CW is my main mode. I would be excited see any improvements in this more in EE products. But am I ready to pay 4K instead of 3K for this enhancement? Perhaps not.
So, the global answer, why PIN diodes are still not there? On a same reason, why Telnet and RS-232 still in use. Just small difference - relays are still not obsolete, when Telnet and RS-232 are. And I personally prefer, per say, EE first fix their current "Telnets" and "RS-232s" and only then look at relays.