Holdalls protect the rods at transit. Holdalls for transporting several rods are especially good when they have separating pads. So the rods are protected all the time.
Long and heavy rods like surf cast rods are better and more comfortably protected with a stiffened holdall.
Additional bags offer more space for umbrellas, bite indicators, nets and so on.
Holdalls and bags with carrying handles and padded shoulder straps increase the comfort of the transport.