Hiya @Johnwscott & Welcome To The Cuckoo Community !!!
Depending on How Much you actually would use the Landline its more of a swings and roundabouts issue in my eyes.
I for one use my landline quite a lot at present and for a variety of different call types and its
a godsend having an All Inclusive Call Package with 60 minute redial function on all
calls (including mobile) to stay in control and avoiding spiraling bills above the package price.
So Yes They Are Worth it if You make a lot of calls and see the 0.00 Charge on my
Monthy Itemised bill is glorious 
However if you have limited use of the home phone then you wont get that much
of a extra bill as all Cuckoo calls are Chargeable in a Pay As You Go Form (PAYG).
But i do see what you mean it is a bit offputting when your looking at the
Cuckoo Deal and you cant see these options like other providers offer.
Im sure @Alex will join this Conversation as we’ve had a few Discussions about this exact topic
and its on the To Do List (which gets longer each day i hear)
If You Believe You Will “Be Quids In” Then Cuckoo would love to have you Onboard…and
as the offer is a 30 Day Rolling Contract Your Not Tied Into a Long Contract Like Most
Providers insist on.
The Final Choice is Yours or to quote a Famous Cartoon Eco-Warrior “The Power Is Yours” - Captain Planet.