Why did Angela Merkel support the big migrant wave in 2015?

Angela Merkel would support the big migrant wave not only in 2015 but also in other years because her convictions reflect European solidarity with migrants and refugees. However this is not possible because there are many legislative limitations that arise in case there is uncertainty of the procedures related to accommodating the refugees once they are in. Therefore if anyone would like to see European political leaders in future making same steps as Mrs. Merkel did back then it is necessary that the country is able and prepared to accept the incoming flow of migrants.

At the same time, external factors such as increased terrorist threat, disagreements among global leaders on the issues of top importance do not allow a leader of a country-leader in the region a great degree of flexibility. Unfortunately seeing the concept of otherness growing throughout and within European countries would not allow leaders to make such brave steps. However, if there is a change in Doublin 2 policy which could compensate for the lack of aforementioned flexibility as the countries who neither have conditions to keep many migrants, nor feel it is fair that they should keep this burden in Europe, would support policies that modify or even council Doublin 2