Neuromorphic Visual Systems, such as spike cameras, have attracted considerable attention due to their ability to capture clear textures under dynamic conditions. This capability effectively mitigates issues related to motion and aperture blur. However, in contrast to conventional RGB modalities that provide dense spatial information, these systems generate binary, spatially sparse frames as a trade-off for temporally rich visual streams. In this context, generative models emerge as a promising solution to address the inherent limitations of sparse data. These models not only facilitate the conditional fusion of existing information from both spike and RGB modalities but also enable the conditional generation based on latent priors. In this study, we introduce a robust generative processing framework named SpikeGen, designed for visual spike streams captured by spike cameras. We evaluate this framework across multiple tasks involving mixed spike-RGB modalities, including conditional image/video deblurring, dense frame reconstruction from spike streams, and high-speed scene novel-view synthesis. Supported by comprehensive experimental results, we demonstrate that leveraging the latent space operation abilities of generative models allows us to effectively address the sparsity of spatial information while fully exploiting the temporal richness of spike streams, thereby promoting a synergistic enhancement of different visual modalities.