I can make the same argument about Leia. Her planet gets destroyed and she does nothing. Friends, family, her home, poof, and nothing. Emotionless robot... at least Mace has a pretty dang reason to be emotionless... he is a Jedi... Leia is a human and shows nothing. So why can Mace get bashed for this... but Leia doesn't?
Coz she don't get mad. She get even.
As Princess - leader of the Rebel Alliance, no less - she must maintain perfect grace under unbelievable pressure, and be seen to be doing so. Indeed, in front of Tarkin and Vader, an emotional breakdown would be tantamount to surrender and, indeed, a betrayal. She's just viewed the destruction of a planet, with millions of people being murdered, and for her to succumb to mere emotion would be almost an insult to those killed. As she says later, with perfect composure: "We have no time for our sorrows..."
Leia is a leader for a reason: stoic, brave, commanding. Indeed, it's these very traits that make her such a respected figure - and, pointedly, represent the weakest point in her armour that Han Solo targets when attempting to seduce her. Her 'iciness', her inclination to prioritise the needs of the Alliance above her own ("
We need? Well what about
you need?") and her studied distance from emotion indeed become the very subplot of
The Empire Strikes Back: Han's pet name of 'Your Worship', and constant references to her exalted royal status more broadly, are direct plays upon her denial of self (and deeper denial of her attraction to him) due to the requirements of being a leader. Indeed,
Empire shifts from the icy white terrain of Hoth (where Leia continues to maintain her reserve, albeit with difficulty), to the suggestively gelatinous bowels of an asteroid slug (where Leia succumbs to Han's advances), to the airily warm colours of Cloud City - where Leia finally 'melts' in the steam of the freezing chamber and confesses her love. Coincidence?
So, Leia's perpetual (albeit justified) reserve is thoroughly examined and pursued in the OT; through Kasdan, especially, Leia is no emotionless robot - she is a brave and stoic leader at a cost to herself emotionally, which Solo recognises and addresses and which the OT films slowly chart as driving the awakening on her part. (Indeed, we go from virginal Leia in white in
Star Wars, to the poised elegance of Cloud City Leia in
Empire, to the bump 'n grind of slavegirl Leia in
Jedi. Again, coincidence?)
Leia's emotional conflict between public and private needs is one of the OT's most engaging elements, and a recurring thematic motif throughout all the OT characters.
Mace Windu, on the other hand, is emotionless due to poor writing and lazy casting.