"Thought it best to get a ras. Big mistake."
It was if you wanted direct routeing! The airspace you were transitting through can get very busy. Requesting RAS will almost certainly involve re-routeing so that the controller can fulfil his part of the agreement (attempt to maintain separation). An alternative would have been to request a Radar Information Service (RIS). Under this service you would receive the same information on traffic but no re-routeing as separation would be your responsibility. You then make your own turns for separation as you see fit (after informing the controller of your intention to do so).
You are quite right about the MATZ status to civ pilots, you should not be "instucted" to remain clear, you are only required to remain clear of the ATZ portion. But please bear in mind that aircraft operating in a MATZ may be performing any number of high speed or rapid climb/descent manouevres and this (wrong) instruction to avoid the MATZ was probably made with your well-being at heart.