I'm really getting tired of people saying that.
Ingruber has a good voice and doesn't have to do an imitation. Frankly, I think the director went a little too far with the mimicking in AOA. If Ingruber were in a whole movie, they would just be interjecting a few "Fordisms" here and there, but the rest would be normal talk. Don't think they won't be forcing Alden to speak like HF here and there. The audience has to have SOME connection to the Han Solo character we all know and love. For all we know, that's what the acting coach is for.
AND, what if Ingruber did do a slight imitation all the way through (unlike his YouTube example)? There are a lot of "actors" who have won an academy award for imitation of someone else in a movie. Take Jamie Foxx, for instance. He was totally a comedy actor and pulled off a brilliant performance "imitating" Ray Charles. With the right direction, anything is possible. In my opinion, I think Ron Howard would have been able to pull a great performance out of Ingruber. What could have been...
Also, if Disney is grooming Ingruber for Indiana Jones, he wouldn't be forced to imitate Ford, since Ford is set to reprise the role in the next one. He's more likely the replacement son.