The problem with leasing is if you grow too fast you're stuck, and if you have to make cutbacks you're also stuck with the lease.
This is the real advantage of them. Even if it costs x% more the value of not being stuck with a lease for a long time is definitely worth it. A lot of financial firms in London are moving to them, leases are typically long (10 years with a 5 year break), and with the uncertainty around brexit it makes total sense to transfer the risk to WeWork et al for not much money at all.
I have no clue what terms the UK has, but in Chicago, you can find places all across the spectrum. I've used shared spaces on month-to-month, and I think they can be quite valuable. But once we reached a certain size, we needed to have our own space. Plus, we work in healthcare, so we have other (read:HIPAA) concerns that need to be dealt with as well.
Again, there can be value, and places like WeWork, 1871, Blue1647, et al, serve specific needs. Like I said before, a lawyer and a willingness to hunt for the right space make all the difference. And right now, there's more empty spaces than filled, so it's easier to negotiate something that could even be just yearly...
This is the real advantage of them. Even if it costs x% more the value of not being stuck with a lease for a long time is definitely worth it. A lot of financial firms in London are moving to them, leases are typically long (10 years with a 5 year break), and with the uncertainty around brexit it makes total sense to transfer the risk to WeWork et al for not much money at all.