In addition Team Ninja reminded also of characters appeared just in the DoA2U intro like Shiden and Ayame, making the first also playable, and finally making more relevant also Kasumi alpha (very important on the chart but that had just 1 little and useless cutscene in the original DoA2).
Free Step Dodge
Kronin
Maybe TN could have done a more original work about shiden and Kasumi Alpha, and in general make a better balance for the characters, but all this work was done really thinking to what could wish to see the DoA fans. Guest stars like the VF ones or Ryo are surely good choices, but I think it's normal that it's not what the majority of Team Ninja fans want see.
Kronin
Said this, I don't want convince you of anything: you are off course free to dislike the bosses and to ask for Virtua Fighter characters or Ryo Hazuki for DoA5U 
DoA Dimensions couldn't be the best game of the series, but surely did a good job bringing back all the characters of the series and making them playable. Alpha 152 and Genra had to be playable in the mind of the developers during DoA3 and 4, while many fans of DoA1 wait for years to see again Raidou in the new anime graphic.