Yeah and all those above examples proved to be danger on national or even world scale.
Oh i don't have to imagine what would be broken circle if mages had access to that forbidden knowledge ,in fact it was in first place reason why circle was overrun by abomnations.
I assume you have specific examples on how the free Rivani or Chasind Mages have been a threat to anyone let alone the world? "Forbidden" Magic is only forbidden because the Chantry, a religious organization, says so and uses terror and force to dictate what is "good" and "bad". There is no more method to their madness than any other real world religion that uses the words of a god they can't prove exists to control people along with their hypocritical practices.
When Abominations began killing everyone in the Ferelden Tower the Mages did not know how to stop them. The common and INCORRECT notion is that the only way to stop an Abomination is to kill it as there is no way to separate a Spirit from it's host. The Mages of Rivain and the Avvar KNOW how to protect Mages from Demons and KNOW how to banish hostile Spirits from their hosts. If the Mages in the Ferelden Tower had this "forbidden" knowledge then HUNDREDS of lives, Templars and Mage alike, would have been saved.
The Chantry claims that the goal of the Circle Tower is to protect mages from themselves and that if they leave they will inevitably become blood mages or abominations but yet they IGNORE and write off ACTUAL methods to prevent this as "evil" and "forbidden". There seems to be an erroneous notion on this thread that the Chantry is an unerring authority on Magic. The Chantry is no more an authority on Magic than the Catholic Church is an authority on sex and self control.
The circles possess many books and resources and are more organized and advanced than the primitive mages of the barbarians tribes,or the dalish,they know a lot even about blood magic,and yes only with new knowledge new magics can be created and studied,practical magic is not useful if you wish to advance.
Freedom doesn't equate to organization which is what mages need, organization not meaningless freedom.
The Mages of the Circle have many books and resources on CHANTRY APPROVED Magics. You would not consider any real world library or similar well of information "organized" or "advanced" if they were restricted to only specific information and ignored everything else of relevance, so why the Circle? Circle Mages DO NOT know a lot about Blood Magic. Being a Blood Mage and in many cases even being SUSPECTED of having such knowledge is punishable by death or Tranquility in Chantry dominated societies.
The "primitive" Mages you speak of have developed methods to exorcize Spirits from their hosts, something the "advanced" Mages of the Circle conventionally believe is impossible. Solas, a powerful Mage and alleged god in his own right, states that Dalish Magic is more practical than Magic taught in the Circle because knowledge is not restricted. One would hardly call wandering clans organized and even Solas, who is very critical of the Dalish, thinks of their Magic as superior to the Circle's.
As we know, Magic takes various forms, and the Chantry only allows the average Mage under its heel to practice four approved schools. Anything outside that pretty little box is not allowed and so Cirlce Mages are limited in their capacity to develop new schools and spells unlike the Dalish who developed the powerful Keeper Magics in the aftermath of the Dales destruction or Shapeshifting.
each major disaster in Thedas history was always started by a mage
At the time of Arlathan everyone were mages but i believe that they were watched constantly by their elven gods,Elgar'nan use to punish the elves who abused of their power,but in the Dragon age there are no gods,or such authority
That is absolutely untrue. The civil wars in Ferelden and Orlais were not started by Mages. The destruction of the Dales, twice over, by the Chantry was not started by Mages. The Qunari Wars were not started by Mages and by all accounts Mages were the greatest advantage of the combined nations in their struggle against the Qunari.