i have to agree to some extent, The itemshop pets are pretty bland and not really a major upgrade from the standard "free" pets. The look is pretty bland and the skills are bland. Having a boss as a pet is possible since we already have a few of the mini boss models as pets(the cosmetic pet).
Although not a priority it is something that I would purchase diamonds for, to get a pet that is unique in its look and better in battle than a standard free pet. it doesnt have to be OP though just enough to justify spending $