Isle would work well, but I guess they preferred I as in "E N".

Yeah. I think they chose Ian because it sounded like an e instead of an i

A as in Aisle
B as in Bdellium
C as in Ctenophore
D as in Djembe
E as in Malaise
F as in Halfpenny
G as in Gnome
H as in Honest
I as in Parliament
J as in Jicama
K as in Knuckle
L as in Malmsey
M as in Mnemonic
N as in Solemn
O as in Opossum
P as in Pneumonic
Q as in Lacquer
R as in February
S as in Debris
T as in Gourmet
U as in Antique
V as in its Very difficult to find a word with a silent V
W as in Wrinkle
X as in Bordeaux
Y as in Halcyon
Z as in Rendezvous