Rather obviously, it'll depend on the kind of birding you do. If you like walking huge distances, or confine yourself to woodland, parks etc. a scope might be overkill, or too much to carry. However, i couldn't imagine being without one. I'm on shorelines, estuaries and marshes and a scope is essential for me.
With magnesium/composite bodies, ED glass etc. you don't have to burden yourself too much. There are very convenient ways of carrying them (i use a scopac to walk there and back, but not while birding). A good 60-65mm ED glass scope can be very lightweight and convenient. Once you've had one, you won't go back, i reckon!
As a side issue, there seems to be a swing in the UK to folks walking round with mini or compact bins and the HUGE camera/lens. However, the availability of various forms of phone adaptors for scopes makes digiscoping a relatively cheap option for the scope owner. So, buy the best glass you can afford, and keep your future options open!