I did not see the original review, and am not familiar with the ballet in question, but would not associate 'soft shoe' as having any racial connotations. In fact, when I searched for info, the only reference I can find indicates that it's one of several early dance styles that blended into modern tap dancing. And tap dancing has evolved from many cultures - both European and African.
I think it's important not to read too much into any casting decision. With few exceptions, I think race plays very little role in casting - body type, height, talent, injury status, scheduling and partnering considerations are much more important. I think that a role should be considered independent of the colour of dancers' skin - i.e. if a role or choreography is offensive, it should be offensive irrelevant of the dancer performing it.
I was lucky enough to see Jonathan Pryce in "Miss Saigon", and the whole to-do' about race was, frankly, ridiculous. The character in question was actually half Vietnamese-half French, so casting a Vietnamese (or Asian) in the role would have been no less correct than casting a Caucasian. To be honest, I think the race issue was a smokescreen - the AEA didn't want a foreign performer taking the role, but since Pryce had an impressive resume by that point, they knew they would have a hard time refusing him based on the 'not well known enough' bit.
The AEA, while certainly worthy, has made some pretty big goofs regarding the allowing/rejecting of foreign performers before. Some years ago they put up a lot of resistance about letting a West End revival of Oklahoma transfer to Broadway with the existing lead cast. By the time they relented, the dancer/singer/actor in the male lead had gotten a movie role and thus wasn't available for the Broadway run. Less than a half decade later that actor - none other than Hugh Jackman - has both won a Tony for another role and hosted the Tony Awards (two or three time now).
I personally don't think we need 'companies of colour', but don't see anything wrong with DTH or Alvin Ailey. They simply celebrate one facet of American culture and provide opportunities for some fantastic dancers in pretty impressive choreography. Though, I think the dissolution of DTH has pretty much proved that it's probably not needed, given that almost all the former DTH dancers seem to have successfully found jobs around the globe - everywhere from Scotland to England to California to New York. I think the Alicia Graf issue was overblown - she's wonderfully talented, but very tall. And tall male dancers are not a common commodity in the US. I don't think it would have been fair for a company to hire her, only to have her 'on the bench' for most of the season because there weren't enough tall partners.
Yes, companies in the US tend to be white (different issue often in Europe and Australia because of passport based hiring limitations), but I think the real issue is not hiring practices at company level, but lack of diversity in young dancers. I don't think ballet is perceived as cool by kids these days, much less in African-American communities. Ballet is perceived as white and elite - if we can get rid of those misconceptions, we'll make some headway. Perhaps then, Arthur Mitchell would be better in running a school and doing community projects rather than trying to resurrect DTH. If the DTH school can make ballet culturally and financially possible for young African Americans and have results in the form of dancers in major companies, then ballet will seem more acceptable to youngsters.
There are also financial barriers - classes cost money and take away time from after school jobs. Additionally, I think body type does play a role - girls of African-American heritage generally begin puberty at an earlier age. Hips and a bust don't usually go with ballet - and dressing in a form-fitting leotard & tights an be awkward & potentially embarrassing when you are going through pubertal changes. Which might be why - it seems to me - that there are many more African American men in ballet companies than women.