You seem be concerned that people may judge the quality of your thesis in part based on the length of the acknowledgments section. I don't think that anyone will do that.
You may be missing a required acknowledgment of one or more grants from a funding agency.
A separate question is whether you have overlooked people who could to be acknowledged in your thesis, or whether it would be appropriate to include a more specific and detailed acknowledgment of the individuals you are acknowledging. As the Ph.D. is the culmination not only of years of research but of years of your life, it's not unusual to think more broadly regarding acknowledgments than you would for a paper. You may want to include, for instance:
- Faculty outside of your committee or university who also mentored you or gave helpful comments and suggestions;
- Anyone who developed code that you used in your thesis;
- People who helped you do a better job with the writing itself, e.g. through teaching you better grammar, better Latex skills, etc.;
- Family members (particularly a spouse) who have supported you during your doctoral work or inspired you to be a scholar;
- Fellow students who have given you encouragement or proofread or otherwise commented on your work.
I suppose you can go too far in being inclusive, and perhaps the example you linked does, though I doubt anyone will get very upset about that either.
In my own acknowledgments I tried to be rather specific about what each of these individuals did, or how I benefitted from their help. For instance, I acknowledged my advisor
...not only for providing continual support and guidance, but especially for allowing (and even enthusiastically encouraging) me to pursue research that I found fascinating but that is only indirectly related to his own research program.
Some of these kinds of acknowledgments would be considered out of place in a journal article, so the thesis gives you an opportunity that you may never get again (unless you publish a book) to express gratitude to these individuals in a somewhat official way. You have nothing to lose by being more inclusive in expressing your gratitude, and you may make someone who reads it very happy by including them.