Well, Marshmallow fixed a lot of the security issues that SD cards lead to and many OEM's have gotten the slot to fit in the SIM tray, which would minimize the structural compromises that SD card slots typically present - so an SD card slot, I'm ok with when it is done mindfully. I have the NVIDIA Shield Tablet and Moto X Pure Edition and both of those have SD card slots and I bought them anyway (through I don't use the slot on either device). Huawei could have gotten away with an SD cards slot and we'd probably be okay.
Removable battery has four standard issues that bother me, though some are with the mentality that they promote rather than the actual feature itself.
1. Physical structure compromise. A device with a removable back and/or battery is going to be obviously more than one piece, removing the back is going to weaken the strength of the device and the assembly. The device is going to necessarily be thicker than it otherwise may need to be. On the flip side, a removable back generally leads to a device that is easier to repair should something physically go wrong with the device. The device will have to be built in a way that the battery is accessible, and some design opportunities are missed, in terms of placement and strategies that can mitigate heat and or use more creative battery shapes.
2. The battery is going to be smaller (in terms of capacity) than it would be if the OEM is not restricted to a rectangle that has to be user removable. Modern batteries can be made to conform to different shapes and thus can eek out more capacity from the same total volume form factor (of the device) by using the space better.
3. Removable batteries promote users' poor behavior due to "hot swapping". Many users think they can 'use the battery down to 5% or less, sometimes letting it die - that's cool, pop off the back and put in the other battery and you're good to go!'. With what we've learned about battery health and heat management, this is very bad for the device and having a device that promotes healthy charging habits by not giving the option for hot swapping in some cases is protecting the user from their own ignorance.
4. Removable batteries promote 'battery pulls', (shutting the device off by removing the battery) which can lead to some of the "lag" and other performance issues that people complain about in phones. Having the user use a proper shut down is much better for the device and the user's experience in the long term.
And for both features, like all features, the inclusion takes up resources in terms of time (engineering, software support) and, for anything that is not a Nexus, will require additional software work on firmware updates to ensure smooth integration of legacy features with new software. So, if the OEM's are going to spend some money on batteries and storage, my preference is this: Spend the money on better software and/or battery technology to get us phones that last many, many days or weeks on a 3000 mAh battery. Spend the money on bringing 256 or 512 GB devices to the market - with faster internal storage that doesn't require a $50 or $100 mark up per increase. I'd much rather have a 128GB phone than have a 32GB phone with an SD card slot, even if the SD card slot supports up to 200GB.
Long story short (TLDR), the cost is way too high for these two features and the benefits are less than none for what I value in phones. Both features, to me, are detrimental and that makes the opportunity cost have an unnatural detraction from the same device in all manners except for the exclusion of either or both features. Obviously some users disagree and value those features above the opportunity cost and for them those features become much more important and desirable. Buy what you like, love what you bought