Yeah I don't get the "paid witnesses" thing either and don't really agree with it but to be fair, she's actually being paid $550p/h (mentioned elsewhere) which compared to what the lawyers on both sides are being paid for their work, is likely tiny by comparison.
I guess you have to factor in the idea that she is ONLY actually there at the 'request' of the Apple legal team as their idea of a "design expert", it's not like she was ever a neutral judge/court appointed witness to begin with.
She also has to actually "earn" her money by appearing both credible and not taking hypocritical personal attacks on her credibility/honesty by opposition lawyers personally, which wouldn't be easy when you know the same people attacking your credibility would not only do and say ANYTHING for a buck themselves but also have a vested financial interest in keeping this trial going on as long as possible.
As a jury member on this case you'd have to assume (and likely will/should have it pointed out to you by both legal teams) that all witnesses either side ends up presenting are on similar sorts of payment schemes.
The Samsung Lawyer might think they are clever attacking her credibility based on her "payment" but you'll now probably find the Apple legal team asking the same "payment" questions and getting the same answers from Samsung designated "expert witnesses" so neither side is likely going to benefit from the exposure of "payments", it'll just lead to further juror confusion and end up causing the case to run longer, which surprise surprise suits nobody but the lawyers billing at an hourly rate.
The ones I feel sorry for are the jurors (and potentially their employers) who are paid an absolute bare minimum for their time and service, if they're lucky enough to work for an understanding employer, the employer of the juror ends up having to pay/cover them for work they are not doing while in court.
It ends up being jurors, other companies and taxpayers who end up "footing the bill" for this battle between two large corporations who, considering the battle is all about honesty and credibility, BOTH actually lack, and have proven time and time again, to lack a whole lot of credibility and honesty themselves.
It's the price society pays to protect Intellectual property rights, whether it is actually worth it or not is still up for debate and far more complex and far reaching than one APPLE vs SAMSUNG case.