I think you'd probably have difficulty on most days, as you'd probably miss the traffic in the ground clutter. It is better to be slightly below circuit height
so the circuit traffic is above the horizon and much easier to see.
That is probably true but there is no "approved method" for arriving at say 600ft AGL
Nothing is perfect but anything is better than an OHJ where there is potential traffic in any direction, and some 2/3 of it (assuming a random bearing) will never be visible. Whereas any other approach to the airfield involves scanning a much smaller horizontal angle.
I still think though that a straight in approach is less desireable than a join from a base leg, though.
I agree, though only because breaking off from a base leg (if you see traffic on the downwind leg) is a bit easier than breaking off from a straight in.
For some reason, ATC are not so keen on base joins, when busy. IME they readily give them to competent locals who they know are not going to cause trouble if asked to orbit on the base leg. But I suspect after that orbiting-student fatal at Southend they are going to be even less keen on it.