there was no need for him to mentioning where going via
Don't take that as a literal fact. You need to find a suitable middle ground. Obviously if you're doing a long flight with 50 waypoints, there's no need to mention them all. But at the same time a call like "VFR from Manston to Islay, request crossing" will require a controller with perfect geographical knowledge to assess the impact of your crossing on his CTR or MATZ.
So as far as I'm concerned, include those "via" points that are relevant to the controller, no more no less.