Yep, for one, the band would never have become what it wound up as, period.
PF 1.0 with him was whimsical and child like, with a psychedelic edge, courtesy of "Interstellar Overdrive" and "Astronomy Domine."
His departure was THE driving force for the direction the band would take in years to come, especially on DSotM, WYWH, and TW, but also on the others to one degree or another (Meddle - Fearless - "The idiot turned to face the crowd.").
PF 2.0 was a bit off stride for some time, then, they took their direction for the next three years with their masterpiece song "A Saucerful of Secrets," which begat "Atom Heart Mother," which begat "Echoes."
Then, came DSotm, with its moody soundscapes, powerful lyrics alluding to madness and the pressures of life in general.
WYWH was the most overt homage to the band's lost hero, especially the absolutely sublime "Shine on You Crazy Diamond" and its opening guitar solo that to this day STILL raises the hairs on my arms.
Even "Animals" had some reference to Syd, especially "Pigs on the Wing."
TW was largely about him, although less directly so.
Yes, the band's lyrics and style was heavily influenced by Syd decades after his untimely departure.
Dave's playing was influenced, and he took it in directions few could imagine.
The band would have been more volatile with Syd than without, and quite a different band.
Syd's playing had that quixotic madness to it.
Dave borrowed some of that with skill, expert note bending, and some real soul.
Some notable pieces of Dave's playing for me:
Atom Heart Mother - The opening slide/tremolo in the Floyd-only live performances
A Saucerful of Secrets, Pompeii version - "Celestial Voices" Cosmic violin produced by vibrating the slide down by the pickups
A Saucerful of Secrets, Fillmore West version - "Celestial Voices" section with an Ennio Morricone soundtrack style
Echoes - Seagulls, the climactic emergence from the "underwater" section
Time - Who does not just love this solo?
Shine on - All three solos in the first half are wonderful, especially the first
Shine on (part 8), Oakland Coliseum version - Dave and Snowy White sound so good when they do the tandem playing here that it nearly brings tears to my eyes
Dogs - extended, aggressive playing that is even better live
Comfortably Numb - even those who have never heard the name David Gilmour or Pink Floyd would find it hard to argue against this pile driver of a solo
Shine on, Syd and RIP