The Turkish army should wait for an APC in the class of the boxer, technologically and modularity wise. The current Turkish APC designs are not groundbreaking and with upgrade plans for the ACV-15's and the Kirpi's replacing the M113 in infantry brigades, there should be no rush for a new non-groundbreaking APC, expect of course for the specialized roles.
And for the fact that BMC gets favored over other, more established companies, that has to do with the politco-cultural background of Turkey. Turkey is a hierarchical society and working together in Turkish politics is almost not done. The political leaders all have too large ego's and that is reflective in the way the Turkish politics under-functioned from 1938-2002, hence with the army needing to take control behind the scenes in order not to let Turkey get torn apart by both internal and external forces. There is very little if any horizontal power stratification in Turkish politics and upper-level bureaucratic and thus in order for orders to be effectively carried out, Turkish politics requires a more intimate and closer contact between the President, ministers and with upper-level bureaucratic managers, business leaders and the media than in more egalistic societies such as western-European ones. Combine this with a geo-politically rising Turkey in the 'ghetto' neighborhood of the world, the power structures need to be more vertically solidified in order for the power-structure to keep functioning with enough clout. Hence a presidential system and nepotistic style of rule is more effective than an idealistically (and naive) parliamentarian system and a egalistic but very cumbersome political descisionmaking.
Such is the political reality of Turkey.