Guess what - it's the RARE critic these days who ever sees a penny for their reviews. Yes, we often get comp tickets, but when you factor getting to & from the performance, parking, dinner (because there isn't time between work and the performance to go home) etc., it's usually pretty much break-even (at best). Most of us do it out of our love of dance, and - in places where a decent ticket costs upwards of $75 - to be able to afford more than the occasional performance each year. And of those who are lucky enough to get paid, all but a handful get paid by the review with no guarantee that a review will be accepted or used.
And yes, I try my best to find out the proper casting whenever possible - but often it is one heck of a chore. Sometimes it can take a long time to track down someone from the press relations staff to get the casting, and then sometimes even they don't know. Which, I might add, is usually not their fault - with shrinking staff due to budget cuts, press staff are often stretched thin and last minute cast changes beyond the principal dancers can occur without their knowledge (or after they've gone home). Plus, even when dancers work on a weekend day, press staff may only work at a performance, so for Friday night opening, you might not be able to get a reply to a casting question until Monday. Or the company just changes things without notice - I attended a touring performance for a company without any bios online or in print where a Le Corsaire pdd became a pas de trois. Those of us covering the performance had to get someone from the theatre to go backstage at intermission to find out the name of the mystery third dancer.
Trust me, I want to credit the correct dancers - and the only time I'm usually left stumped are with the uncredited corps or large all-corps ballets performed by unfamiliar companies. But to suggest that it's 100% the job of the reviewer to identify everyone one of 40-100 dancers in a company is completely unfair - the companies and press staff have their role to play.
I do think that press/PR staff and companies could make it easier on themselves sometimes - find out what is actually useful to the press and make use of technology. If I were going to make some suggestions:
1) Create a press blog where you post all press related stuff and that sends automated e-mails to everyone on the press e-mail list when you updated something. I can then go to the site to download images, press releases, casting and can minimize the times I have to contact you to find out something.
2) Try to keep a consistent press ticket policy that can be clearly articulated to critics who are new to your company. Realize that I don't want to do things 'the wrong way', but your 'right way' may be different from that of other companies I've covered. It used to be that most critics worked for a print paper and tended to stay put in one location. Now we tend to write for online outlets, and have other jobs, so we're much more likely to move between cities.
3) Let me know how far in advance you want ticket requests (and by what method) and try to be consistent. I REALLY appreciate those companies who have a consistent policy and/or take the initiative to send out press invites so that I know exactly when you need requests. It is really embarrassing and frustrating for me to find out about request deadlines or press events late in the game, so it's better for all of us to be well informed.
4) Make sure you don't use fancy fonts, formatting etc. in your press releases and/or send me a PDF copy so I don't have to rely on a version where things are all askew or unreadable.
5) Set up a password protected page where you post a few press photos for each production so I don't have to bother you after each performance to get press photos. And if you change the password, let us all know!
6) Try to post casting online, and provide a date of last update so I know when the posted casting was current. And if your company does not provide written inserts or postings of last minute cast changes, please update your online website after performances or send out a quick press blast so I have some written list of the actual cast.
7) Try to get your company to resist overly fancy and hard to navigate websites. I like to be able to easily find a) casting, b) company bios, c) info on each ballet, d) info on theatre locations and transport options and d) bios of other artistic staff. It's amazing how well some companies bury their casting and company rosters. Also, I really like a website where I can see the full roster one page and divided by rank - that way I can check spelling of names without having to click through to multiple pages and quickly scan to see who is in the company and their rank.

Try to get the company to avoid videos on the front page that start without my specifically selecting them. If I have to check the site at work or on the road (iPhone, slow internet connection etc.), I don't want blaring music or a video that slows down my connection.
9) If possible, try to have a member of the press staff positioned at a consistent spot on opening night (or if they're present). It may take me a few performances to get to know your name and face, and it's really great for me to able to find you for a few moments if I have questions about casting or procedures. And it also gives you a chance to ask me questions and let me know if you have any concerns.
10) If you have some time in the off season, try to ask the critics what works for them. Sometimes I find companies go to a lot effort for press things that are of little use to critics, and could save themselves time and money.