Both the Aron HaKodesh and the Mizbe'ach had rings and staves which were inserted into the rings, for carrying purposes. Why didn't the Menorah also have these rings and staves?
My guess is that was was a technical issue; gravity.
The Menorah was 18 Tefachim high, if which the lower half was mainly a narrow stem.
Since the poles had to be low enough that when put on somebody's shoulder the bottom of the Menora would be above the ground, they would have had to be attached to the stem.
Trying to carry a top-heavy Menorah with 1 or 2 poles attached to the lower half of the Menora would mean it would have constantly been at risk of falling over (if you had the strength to lift it right way up in the first place).